Section III. TRICYRTIDA, Haeckel, 1881, Prodromus, p. 426, 434.

Definition.—Cyrtoidea trithalamia, with three-jointed shell, composed of cephalis, thorax, and abdomen, with two separating transverse constrictions, an upper collar, and a lower lumbar constriction.

Synopsis of the Families and Subfamilies of Tricyrtida.

Family LXV. Podocyrtida.

Three radial apophyses.

Mouth open,Theopilida.
Mouth closed,Theoperida.

Family LXVI. Phormocyrtida.

Numerous radial apophyses.

Mouth open,Theophormida.
Mouth closed,Theophænida.

Family LXVII. Theocyrtida.

No radial apophyses.

Mouth open,Theocorida.
Mouth closed,Theocapsida.

Family LXV. Podocyrtida.

Three radial apophyses.

Mouth open,
Theopilida.
Mouth closed,
Theoperida.

Family LXVI. Phormocyrtida.

Numerous radial apophyses.

Mouth open,
Theophormida.
Mouth closed,
Theophænida.

Family LXVII. Theocyrtida.

No radial apophyses.

Mouth open,
Theocorida.
Mouth closed,
Theocapsida.

Family LXV. Podocyrtida, n. fam. (Pl. [67], [68], [71]-[73]).

Theopilida et Theoperida, Haeckel, 1881, Prodromus, p. 435, 436.

Definition.—Tricyrtida triradiata. (Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, and bearing three radial apophyses.)

The family Podocyrtida, composed of the Theopilida and Theoperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed and triradial, bearing three external apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Theopilida is a simple wide opening, in the Theoperida closed by a lattice-plate. The latter are derived from the former by development of this closing plate. The phylogenetic origin of the Podocyrtida may be found in the Tripocyrtida, from which they are derived by development of an abdomen. But there are also some forms, which may be derived directly from the Plectoidea, and the origin of some other forms seems to be doubtful.

The Podocyrtida represent one of the largest groups of Cyrtoidea, very rich in numerous species, which are partly very common and widely distributed. A large number of living and fossil species has already been described and figured by Ehrenberg, (1872, 1879, loc. cit.). These mainly belong to his genera Podocyrtis, Pterocanium, Rhopalocanium, Lithornithium, &c., and many of them are very characteristic and common forms, in which the triradial structure of the three-jointed shell is visible at first view. We distinguish here twenty genera and one hundred and fifty species. The majority have a shell with a simple wide open mouth (Theopilida, fourteen genera and one hundred and eighteen species), in the minority the mouth is closed by lattice-work (Theoperida, six genera and thirty-two species).

The three joints of the shell have in the majority of Podocyrtida such a proportion that the cephalis is the smallest, the abdomen the largest, and the thorax between them intermediate in size. The cephalis bears almost constantly an apical horn; this is rarely reduced or lost; sometimes two or more horns are developed. The three radial apophyses arise originally from the base of the cephalis, and may from this point run along the shell-wall embedded in the lattice-plate of the thorax and the abdomen. They leave the latter at very different points, and form either lateral wings or terminal feet, sometimes both together. They are either solid or latticed, sometimes also branched, and of very various shape. Often only the three terminal feet surrounding the mouth have remained, whilst the ribs have disappeared.

Many species of this large family are very variable and connected with other different species by numerous transitional forms; the distinction of the genera described is also often very difficult.

Synopsis of the Genera of Podocyrtida.

I. Subfamily Theopilida.

(Podocyrtida aperta.)

Terminal mouth of the shell a simple wide opening.

A. Three free limbs or wings on the thorax (partly also on the abdomen).No free external appendages on the abdomen.Three wings of the thorax solid.Wings arising from the thorax,582. Pterocorys.
Three ribs enclosed in the wall of the thorax,583. Theopilium.
Wings arising free from the collar stricture,584. Corocalyptra.
Three wings of the thorax latticed.Wings not prolonged into the cephalis,585. Dictyoceras.
Wings prolonged into the cephalis,586. Pteropilium.
Free appendages on the abdomen.Three ribs prolonged into three terminal feet.Ribs and feet solid,587. Theopodium.
Ribs and feet latticed,588. Pterocanium.
Three free wings on the thorax. Numerous terminal feet.Wings and feet solid,589. Pterocodon.
Wings and feet latticed,590. Dictyocodon.
B. Free appendages not on the thorax, only on the abdomen.Abdomen with three ribs and three feet,591. Pleuropodium.
Abdomen without lateral ribs, with three terminal feet.Three feet solid, simple,592. Podocyrtis.
Three feet solid, ramified,593. Thyrsocyrtis.
Three feet latticed,594. Dictyopodium.

II. Subfamily Theoperida.

(Podocyrtida clausa.)

Terminal mouth of the shell closed by a lattice-plate.

Three lateral wings only on the thorax,Wings solid,595. Lithornithium.
Wings latticed,596. Sethornithium.
Three lateral wings beginning from the thorax and prolonged into the abdomen,597. Theopera.
Three wings only on the abdomen.Spell spindle-shaped, with three lateral wings on the abdomen.No horn on the basal pole,598. Rhopalocanium.
Basal pole of the shell with a horn,599. Rhopalatractus.
Shell three-sided pyramidal, with three terminal-feet on the basal corners,600. Lithochytris.

I. Subfamily Theopilida.

(Podocyrtida aperta.)

Terminal mouth of the shell a simple wide opening.

A. Three free limbs or wings on the thorax (partly also on the abdomen).
No free external appendages on the abdomen.
Three wings of the thorax solid.
Wings arising from the thorax,
582. Pterocorys.
Three ribs enclosed in the wall of the thorax,
583. Theopilium.
Wings arising free from the collar stricture,
584. Corocalyptra.
Three wings of the thorax latticed.
Wings not prolonged into the cephalis,
585. Dictyoceras.
Wings prolonged into the cephalis,
586. Pteropilium.
Free appendages on the abdomen.
Three ribs prolonged into three terminal feet.
Ribs and feet solid,
587. Theopodium.
Ribs and feet latticed,
588. Pterocanium.
Three free wings on the thorax. Numerous terminal feet.
Wings and feet solid,
589. Pterocodon.
Wings and feet latticed,
590. Dictyocodon.
B. Free appendages not on the thorax, only on the abdomen.
Abdomen with three ribs and three feet,
591. Pleuropodium.
Abdomen without lateral ribs, with three terminal feet.
Three feet solid, simple,
592. Podocyrtis.
Three feet solid, ramified,
593. Thyrsocyrtis.
Three feet latticed,
594. Dictyopodium.

II. Subfamily Theoperida.

(Podocyrtida clausa.)

Terminal mouth of the shell closed by a lattice-plate.

Three lateral wings only on the thorax,
Wings solid,
595. Lithornithium.
Wings latticed,
596. Sethornithium.
Three lateral wings beginning from the thorax and prolonged into the abdomen,
597. Theopera.
Three wings only on the abdomen.
Spell spindle-shaped, with three lateral wings on the abdomen.
No horn on the basal pole,
598. Rhopalocanium.
Basal pole of the shell with a horn,
599. Rhopalatractus.
Shell three-sided pyramidal, with three terminal-feet on the basal corners,
600. Lithochytris.

Subfamily 1. Theopilida, Haeckel, Prodromus, p. 435.

Definition.—Podocyrtida with the terminal mouth of the shell open (vel Tricyrtida triradiata aperta).

Genus 582. Pterocorys,[[199]] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, free lateral wings arising from the sides of the thorax.

The genus Pterocorys, comprising numerous and some very common species, may be one of the oldest and most primitive Theopilida, and is perhaps the common ancestral form of all Tricyrtida. It exhibits three free lateral wings, arising from the sides of the thorax, like Lithomelissa among the Dicyrtida, and may be derived directly from this genus by development of an abdomen. The latter is commonly cylindrical or ovate, with a wide open mouth, whilst the thorax is either campanulate or three-sided and pyramidal.

Subgenus 1. Pterocyrtidium, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 531.

Definition.—Horn of the cephalis simple. Abdomen not prolonged into a narrow tube.

1. Pterocorys campanula, n. sp. (Pl. [71], fig. 3).

Shell campanulate, with two distinct strictures. Length of the three joints = 2 : 3 : 2, breadth = 2 : 4 : 6. Cephalis subovate, with a pyramidal horn of the same length. Thorax subconical, in the middle zone with three conical, horizontal wings, shorter than the cephalis, from which three thin ribs are decurrent to the mouth. Abdomen short and much dilated, with wide, truncate mouth. Pores nearly equal, small, subregular, circular.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.04; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Central Pacific, Stations 266 to 274, surface.

2. Pterocorys carinata, Haeckel.

Eucyrtidium carinatum, Haeckel, 1862, Monogr. d. Radiol., p. 322, Taf. vii. figs. 4-7.

Shell subovate, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis ovate, with a pyramidal horn of twice the length. Thorax campanulate, with three decurrent crests, from which in the lower part three small conical wings arise, shorter than the cephalis. Abdomen barrel-shaped, inflated, with wide, truncate mouth. Pores everywhere equal, small, regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.25, b 0.05, c 0.075; breadth, a 0.25, b 0.09, c 0.1.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; many stations, surface.

3. Pterocorys sabæ, Haeckel.

Pterocanium sabæ, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. x. fig. 17.

Shell campanulate or subconical, with two sharp strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of the same length. Thorax subconical, in the lower third with three small, conical, little curved wings, shorter than the cephalis. Abdomen dilated towards the wide, truncate mouth. Pores subregular, circular, gradually increasing in size from the collar towards the mouth.

Dimensions.—Length of the three joints, a 0.025, b 0.06, c 0.08; breadth, a 0.02, b 0.08, c 0.09.

Habitat.—Indian Ocean, Zanzibar, 2200 fathoms (Pullen).

4. Pterocorys columba, n. sp. (Pl. [71], fig. 2).

Shell subovate, with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 3 : 7 : 7. Cephalis hemispherical, with a curved conical horn of the same length. Thorax inflate, in the middle zone with three pyramidal downwardly divergent wings of nearly the same length. Abdomen short, inflate, little constricted towards the wide, truncate mouth. Pores all nearly equal, subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.04; breadth, a 0.03, b 0.07, c 0.07.

Habitat.—North Pacific, Station 237, surface.

5. Pterocorys falcifera, Haeckel.

Pterocanium falciferum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 107, Taf. iv. fig. 15.

? Pterocanium bibrachiatum, Stöhr, 1880, Palæontogr., vol xxvi. p. 106, Taf. iv. fig. 14.

Shell subovate, with two distinct strictures. Length of the three joints = 2 : 6 : 5, breadth = 3 : 9 : 10. Cephalis subspherical, with a conical horn of the same length. Thorax hemispherical, thick-walled, rough, with three stout triangular wings, which are about as long as the shell, and curved downwards, with upper convexity. Abdomen ovate, cylindrical, with wide, truncate mouth. Pores irregular, roundish, large and small intermingled; at the base of the abdomen (below the lumbar girdle) a circle of somewhat oblong, quadrangular pores.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.05; breadth, a 0.03, b 0.09, c 0.1.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr); Caltanisetta (Haeckel).

6. Pterocorys aquila, n. sp. (Pl. [71], fig. 5).

Shell ovate, with two deep strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 8 : 6. Cephalis hemispherical, with a slender curved horn of three times the length. Thorax hemispherical, campanulate, spiny, prolonged above the lumbar girdle into three stout, three-sided prismatic wings, which are longer than the shell, fenestrated at the base, and S-shaped, curved. Abdomen barrel-shaped, with wide, truncate mouth. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.03, b 0.16, c 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Pterocorys hirundo, n. sp. (Pl. [71], fig. 4).

Shell slender, ovate, with two deep strictures. Length of the three joints = 1 : 4 : 4, breadth = 2 : 5 : 5. Cephalis hemispherical, with a large pyramidal horn longer than the half shell. Thorax conical, spiny, prolonged above the lumbar girdle into three slender, triangular, prismatic wings, which are about as long as the shell, and slightly curved downwards, with lower convexity. Abdomen inflated, with wide, truncate mouth. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.08; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

8. Pterocorys barbadensis, Haeckel.

Pterocanium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 6.

Pterocyrtidium barbadense, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi., Taf. xxxiii. fig. 29, a, b.

Shell slender, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 4, breadth = 2 : 4 : 4. Cephalis hemispherical, with a stout pyramidal horn of twice the length. Thorax campanulate-conical, in the lower half with three divergent, angular wings, which are slightly curved downwards, and as long as the thorax. Abdomen cylindrical, with wide, truncate mouth. Pores small, subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.04, b 0.07, c 0.07.

Habitat.—Fossil in Barbados.

9. Pterocorys apis, Haeckel.

Pterocodon apis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 3.

Shell slender, smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 3 : 4. Cephalis hemispherical, with a curved, conical horn of three times the length. Thorax very small, with three nearly horizontal, conical wings, which are slightly curved downwards, and twice as long as the thorax. Abdomen cylindrical, three times as long as the thorax, with wide, truncate mouth. Pores small, subregular, circular. Differs from all other species in the very small size of the thorax; the abdomen is broken off in Ehrenberg's figure.

Dimensions.—Length of the three joints, a 0.15, b 0.02, c 0.06; breadth, a 0.02, b 0.03, c 0.04.

Habitat.—Cosmopolitan; Atlantic, Pacific, many stations; also fossil in Barbados.

10. Pterocorys melitta, Haeckel.

Rhopalocanium ornatum, Bury, 1862, Polycystins of Barbados, Taf. vi. fig. 4.

Shell slender, smooth, with two deep strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 2. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax broad and short, loaf-shaped, with three conical wings, which are horizontally expanded, and half as long as the shell. Abdomen cylindrical, with wide, truncate mouth. Pores small, subregular, circular.

Dimensions.—Length of the three joints, a 0.025, b 0.03, c 0.09; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Fossil in Barbados.

11. Pterocorys turgida, Haeckel.

Lychnocanium turgidum, Ehrenberg, 1885, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 6.

Shell thick-walled, pear-shaped, smooth, with sharp collar stricture. The lumbar stricture is not distinct externally, but is represented by a broad, internal, annular septum. Length of the three joints = 1 : 6 : 3, breadth = 2 : 7 : 6. Cephalis hemispherical, with a stout pyramidal horn of the same length. Thorax and abdomen together pear-shaped, inflated. Immediately above the lumbar stricture three stout, conical, lateral wings, as long as the cephalis, arise. Mouth very small, about as broad as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.06; breadth, a 0.03, b 0.13, c 0.12.

Habitat.—Fossil in Barbados.

Subgenus 2. Pterosyringium, Haeckel.

Definition.—Horn of the cephalis simple. Abdomen prolonged into a narrow cylindrical tube.

12. Pterocorys tubulosa, n. sp. (Pl. [68], fig. 6).

Pterosyringium tubulosum, Haeckel, 1879, Atlas, loc. cit.

Shell thick-walled, rough, with two slight strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 3 : 1. Cephalis hemispherical, with a conical horn of the same length. Thorax ovate, in the upper half with three ribs, arising into short, triangular, slightly prominent wings. Abdomen prolonged into a cylindrical, narrow tube of the same length as the thorax. Terminal mouth very narrow. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.12; breadth, a 0.03, b 0.09, c 0.03.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

13. Pterocorys pipetta, n. sp.

Shell thin-walled, smooth, with two slight strictures. Length of the three joints = 1 : 6 : 3, breadth = 1 : 3 : 1. Cephalis ovate, with a conical horn of twice the length. Thorax ovate, in the middle zone with three conical wings of the same length, curved slightly downwards (like those of Pterocorys columba, Pl. [71], fig. 2). Abdomen constricted into a cylindrical tube half as long as the thorax, with narrow mouth. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.06; breadth, a 0.02, b 0.06, c 0.02.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Subgenus 3. Pterocorythium, Haeckel.

Definition.—Horn of the cephalis double or multiple. Abdomen not prolonged into a narrow tube.

14. Pterocorys rhinoceros, n. sp. (Pl. [71], fig. 1).

Shell very delicate and thin-walled, with two sharp strictures. Length of the three joints = 2 : 10 : 3, breadth, 3 : 11 : 9. Cephalis obtuse, conical, with two divergent, conical horns of equal length. Thorax triangular, pyramidal; from its three edges there arise on the middle joint three conical descending wings (little larger than the horns), and from the base of each wing descend two divergent crests, forming at the sides of the pyramid three rounded lobes. Abdomen short, cylindrical, with wide, truncate mouth. Network of the whole shell very delicate, with very small and numerous, regular, circular, hexagonally-framed pores.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.03; breadth, a 0.03, b 0.11, c 0.09.

Habitat.—Central Pacific, Stations 270 to 274, surface, and in various depths.

15. Pterocorys prismatica, n. sp.

Shell very delicate and thin-walled throughout, with fine fenestration similar to that of the preceding species, but differing from it in the form of the abdomen, which is much larger, three-sided and prismatic; three edges of the prism decurrent from the bases of the three short wings. Length of the three joints = 1 : 4 : 5, breadth = 2 : 6 : 6. No lobes at the thorax. Mouth wide open, truncate, triangular.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.04, b 0.12, c 0.12.

Habitat.—South Pacific, Station 288, surface.

16. Pterocorys tricornis, n. sp.

Shell spiny, with two deep strictures. Length of the three joints = 1 : 5 : 3, breadth = 1 : 7 : 5. Cephalis subspherical, with three stout, pyramidal, divergent horns, which are three times as long, and bear three serrated edges. Thorax three-sided pyramidal, spiny; its three edges prolonged at the girdle into three stout, triangular, prismatic wings of the same length, little curved. Abdomen short, cylindrical, with wide open, truncate mouth. Pores irregular, polygonal, roundish.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.06; breadth, a 0.03, b 0.14, c 0.1.

Habitat.—North Pacific, Station 244, surface.

17. Pterocorys zittelii, Haeckel.

Pterocyrtidium zittelii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 531, 540, Taf. xxxiii. figs. 28, a, b.

Shell thin-walled, rough, with two slight strictures. Length of the three joints = 2 : 5 : 7, breadth = 3 : 5 : 5. Cephalis hemispherical, armed with a very large, prismatic, vertical horn, which is half as long as the shell, and at its base surrounded by several (three to five) shorter, upwardly diverging horns. Thorax campanulate, in the upper half with three short, downwardly diverging, conical wings. Abdomen subcylindrical, with wide, truncate mouth. Pores small, subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.03, b 0.05, c 0.05.

Habitat.—Fossil in Barbados.

18. Pterocorys macroptera, n. sp.

Shell thin-walled, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 3. Cephalis hemispherical, armed with two larger and six to eight smaller, conical, divergent horns of different lengths. Thorax three-sided pyramidal; its three edges prolonged into three very large diverging wings, which are slender, three-sided, prismatic, and nearly twice as long as the shell. Abdomen short, cylindrical, with wide, truncate mouth. Pores irregular, roundish, in the middle part of the shell (on both sides of the girdle) much larger than in the upper and lower part.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.06; breadth, a 0.04, b 0.12. c 0.1.

Habitat.—South Atlantic, Station 335, surface.

Genus 583. Theopilium,[[200]] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three lateral ribs enclosed in the wall of the thorax, without free lateral or terminal appendages.

The genus Theopilium differs from all the other Theopilida in the absence of free external appendages; it has neither lateral wings nor terminal feet, but three divergent ribs are enclosed in the wall of the thorax. It agrees in this character with the Dicyrtid Lamprodiscus, and may be derived directly from this by development of an abdomen.

1. Theopilium tricostatum, n. sp. (Pl. [70], fig. 6).

Shell flatly conical, smooth. Length of the three joints = 1 : 4 : 2, breadth = 2 : 6 : 10. Cephalis subspherical, with a thin oblique horn of the same length. Thorax with three stout ribs in its wall, and with subregular, hexagonal pores increasing in size towards the girdle. Abdomen flatter than the thorax, without ribs, nearly horizontal, with subregular, square pores, disposed in four to six concentric, subcircular series of different sizes; decreasing in size towards the wide open mouth. Seen from the side, this species resembles Corocalyptra agnesæ, (Pl. [59], fig. 3).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Central Pacific, Stations 260 to 274, surface.

2. Theopilium triradiatum, n. sp.

Shell flatly conical, smooth, in general of the same form as, and with similar fenestration to, the preceding species, but different in the proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 4 : 6. Cephalis hemispherical, with two divergent, thin horns of the same length. Thorax more elevated, about as high as broad. The three divergent ribs are not limited to the thorax, but prolonged through the whole abdomen, the outline of which is a prolongation of that of the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.05; breadth, a 0.05, b 0.1, c 0.15.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Theopilium cranoides, Haeckel.

Eucyrtidium cranoides, Haeckel, 1862, Monogr. d. Radiol., p. 320, Taf. vii. figs. 1-3.

Shell campanulate-conical, smooth. Length of the three joints = 2 : 5 : 4, breadth = 3 : 9 : 10. Cephalis ovate, with a straight, excentric, prismatic horn of the same length. The campanulate thorax is separated from it by no external collar stricture, but by an internal septum. From the base of the horn arise three divergent radial ribs, running in the wall of the two first joints to the lumbar stricture (loc. cit., Taf. vii. fig. 3). Abdomen short and wide, without ribs. Pores rather large, regular, circular, quincuncial, in the cephalis smaller. Central capsule four-lobed.

Dimensions.—Length of the three joints, a 0.027, b 0.054, c 0.047; breadth, a 0.03, b 0.09, c 0.1.

Habitat.—Mediterranean (Messina), surface.

Genus 584. Corocalyptra,[[201]] n. gen.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, free, lateral wings, arising from the collar stricture between cephalis and thorax.

The genus Corocalyptra comprises a small number of very elegant hat-shaped Tricyrtida, which resemble greatly Eucecryphalus among the Dicyrtida. As in the latter, three free, radial spines, or simple wings, corresponding to the three basal feet of Cortina, arise from the collar stricture between the small hemispherical cephalis and the large, flatly conical thorax. Corocalyptra differs from Eucecryphalus, its ancestral form, in the development of a flat and broad abdomen, which is a prolongation of the thorax, and may be compared to the brim of a hat.

1. Corocalyptra agnesæ, n. sp. (Pl. [59], fig. 3).

Shell flatly conical or hat-shaped. Length of the three joints = 1 : 4 : 2, breadth = 2 : 8 : 12. Cephalis hemispherical, with an oblique, small, conical horn of the same length. From the slight collar stricture arise three slender, conical feet of equal length, twice as long as the apical horn, nearly horizontally divergent. Lateral outline of the conical thorax straight, of the flatter abdomen convex; the smooth margin of the abdomen turned inwards. Network delicate, with subregular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.15, c 0.24.

Habitat.—Central Pacific, Station 270, surface.

2. Corocalyptra elisabethæ, n. sp. (Pl. [59], fig. 10).

Shell flatly conical, hat-shaped, very similar to the preceding species, but with different proportions. Length of the three joints = 1 : 4 : 2; breadth = 1 : 7 : 10. Cephalis very small, with an oblique horn of the same length. The three feet are of different sizes, the caudal odd foot being twice as long as the two lateral, which are equal to the horn. Lateral outline of the campanulate thorax convex, of the flatter abdomen less convex. Margin of the mouth flat.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth a 0.02, b 0.14, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Corocalyptra emmæ, n. sp. (Pl. [59], fig. 4).

Shell nearly conical, hat-shaped. Length of the three joints = 1 : 3 : 1, breadth = 1 : 5 : 7. Cephalis hemispherical, with a straight horn of the same length. Feet of the collar larger than in the preceding species, the two lateral smaller being directed upwards, the larger odd caudal downwards. Thorax slightly campanulate; its hexagonal meshes two to four times as large as those of the short, convex abdomen, which is turned inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.03; breadth, a 0.025, b 0.13, c 0.17.

Habitat.—Central Pacific, Station 273, surface.

4. Corocalyptra margarethæ, n. sp.

Shell nearly conical, hat-shaped, very similar to the preceding species, but with much more delicate hexagonal network, with thread-like bars. Length of the three joints = 1 : 7 : 2, breadth = 1 : 10 : 12. Cephalis hemispherical, with six bristle-shaped spines of half the length of the shell; three horns divergent upwards, and three alternating feet divergent downwards. Thorax nearly conical. Abdomen flatter.

Dimensions.—Length of the three joints, a 0.015, b 0.1, c 0.03; breadth, a 0.02, b 0.15, c 0.18.

Habitat.—North Pacific, Station 236, surface.

5. Corocalyptra ludovicæ, n. sp.

Shell flatly campanulate or hat-shaped. Length of the three joints = 1 : 4 : 3, breadth = 2 : 7 : 10. Cephalis hemispherical, with six bristle-shaped spines, about one-fourth to one-third as long as the shell; three horns diverging upwards, and three alternate feet diverging downwards. Thorax nearly conical. Abdomen much larger than in all preceding species, inflated, with convex, lateral outline; its mouth-edge curved inwards. The network is much finer than in the similar Corocalyptra emmæ (Pl. [59], fig. 4), and the abdomen is relatively twice as long and broad.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.04, b 0.14, c 0.2.

Habitat.—Central Pacific, Station 271, surface.

Genus 585. Dictyoceras,[[202]] Haeckel, 1862, Monogr. d. Radiol., p. 333.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the sides of the thorax, which are not prolonged into the cephalis.

The genus Dictyoceras and the following Pteropilium agree with the two preceding genera in the possession of three lateral wings on the sides of the thorax; but whilst these in the latter are simple solid spines, they are in the former vertical fenestrated plates. Dictyoceras may be derived from Pterocorys by development of a vertical lattice-plate between the thorax and the three free lateral spines arising from it.

1. Dictyoceras insectum, n. sp. (Pl. [71], figs. 6, 7).

Shell with two distinct strictures. Length of the three joints = 1 : 3 : 2, breadth = 2 : 4 : 3. Cephalis hemispherical, with a slender pyramidal horn of twice the length. Thorax subspherical, in the upper half with three divergent lattice-wings of the same length, each of which represents a slender, fenestrated, three-sided pyramid. Abdomen subovate, with wide, truncate mouth (in the figured specimen broken off). Pores circular, small, of different sizes.

Dimensions.—Length of the three joints, a 0.025, b 0.055, c 0.04; breadth, a 0.035, b 0.08, c 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

2. Dictyoceras formica, n. sp. (Pl. [71], fig. 8).

Shell with obliterate collar, but deep lumbar stricture. Length of the three joints = 1 : 2 : 3, breadth = 2 : 5 : 4. Cephalis conical, with an oblique curved horn of the same length. Thorax with three vaulted swellings between the three prominent, diverging lattice-wings, the apex of which is prolonged downwards into a solid curved spine, half as long as the inflated abdomen. Mouth little constricted. Pores irregular, roundish, of different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.03, b 0.1, c 0.09.

Habitat.—North Atlantic, Station 353, surface.

3. Dictyoceras melitta, n. sp. (Pl. [71], fig. 9).

Shell with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 6 : 5. Cephalis subspherical, with two conical divergent horns of the same length. Thorax three-sided pyramidal, the three edges prolonged into three lattice-wings of the same form, with short, terminal spines. Abdomen inflated, subovate, with constricted mouth. Pores small, regular, circular, of equal size, with very thin bars.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.04, b 0.18, c 0.15.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

4. Dictyoceras bombus, n. sp. (Pl. [71], fig. 10).

Shell with deep collar, but evanescent lumbar stricture. Length of the three joints = 1 : 5 : 3, breadth = 1 : 6 : 7. Cephalis subspherical, with a conical horn of the same length. Thorax campanulate, with three short and broad, triangular lattice-wings, the upper edge of which is nearly horizontal, the lower nearly vertical and decurrent from the height of the collar to the lumbar stricture. Abdomen inflated, with constricted mouth of half the breadth. Pores small, subregular, circular, of nearly equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.06; breadth, a 0.025, b 0.12, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Dictyoceras virchowii, Haeckel.

Dictyoceras virchowii, Haeckel, 1862, Monogr. d. Radiol., p. 333, Taf. viii. figs. 1-5.

Lithornithium dictyoceras, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1860, p. 840.

Shell with two distinct strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with an oblique curved horn of the same length. Thorax conical, with three broad, triangular lattice-wings different in size and direction, two of which are directed outwards, the third downwards—each terminated by a strong spine. Abdomen oblique, inflated, with wide open, truncate mouth. On the shell surface some few conical spines are scattered. Pores irregular, roundish, of different sizes. On the peculiar symmetry of this remarkable form, compare the detailed description in my Monograph.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.02, b 0.1, c 0.12.

Habitat.—Mediterranean, Messina, surface.

Genus 586. Pteropilium,[[203]] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the sides of the thorax, prolonged into the horn of the cephalis in the form of three vertical, free cephalic wings.

The genus Pteropilium differs from the preceding closely allied Dictyoceras in the development of three free, vertical, latticed cephalic wings, expanded between the apical horn of the cephalis and the three wings of the thorax; they may be direct prolongations of the latter. Pteropilium, however, may also be derived directly from the Dicyrtida Callimitra or Clathrocorys by development of an abdomen. All these interesting forms are closely allied to the Plectoidea.

Subgenus 1. Clathropilium, Haeckel, 1881, Prodromus, p. 435.

Definition.—Thorax completely latticed, without three larger lateral holes between the three wings.

1. Pteropilium stratiotes, n. sp. (Pl. [70], figs. 9, 10).

Shell thin-walled, with two deep strictures. Length of the three joints = 1 : 5 : 4, breadth = 2 : 6 : 9. Cephalis hemispherical, with a vertical, straight, prismatic horn of three times the length. Thorax inflated, oblique, with three slender, nearly straight, widely divergent ribs, beginning from the collar stricture and united in its centre with the centripetal prolongation of the horn. The basal half of the three ribs is enclosed in the thorax wall, whilst the distal half lies outside it, and is connected with its lower half only by two divergent, reticulated wings. The upper edge of the ribs is connected with the occipital horn by a vertical, loosely reticulated, triangular wing. Abdomen half as long as the thorax, also of irregular and oblique form, with knee-shaped outline and a wide, truncate mouth. Network with irregular polygonal, for the most part quadrangular, meshes, separated by thin bars and forming irregular transverse rows. Some stronger, vein-like ribs ramify in the wall, diverging towards the mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.08; breadth, a 0.04, b 0.12, c 0.18.

Habitat.—Central Pacific, Station 271, surface.

2. Pteropilium hoplites, n. sp.

Shell in the general form and in the irregular, quadrangular fenestration similar to the preceding species, but more heavy and with different proportions. Length of the three joints = 1 : 6 : 4, breadth = 2 : 6 : 8. Cephalis twice as broad as in Pteropilium stratiotes. Thorax more slender and subovate. Abdomen truncate, conical, gradually dilated, with straight, non-geniculate outline. Network coarser, with larger square meshes and thicker bars.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.08; breadth, a 0.05, b 0.12, c 0.16.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Pteropilium eques, n. sp.

Shell in the general form and in the irregular, quadrangular fenestration similar to those of the two preceding species, but more slender and with different proportions. Length of the three joints = 1 : 3 : 2, breadth = 2 : 4 : 4. Cephalis flatter. Thorax subconical, also flatter. Abdomen short, cylindrical, with straight outline. Network looser than in the two preceding species, with larger square meshes and thinner bars.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.06; breadth a 0.06, b 0.12, c 0.12.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 2. Arachnopilium, Haeckel, 1881, Prodromus, p. 435.

Definition.—Thorax with three large lateral holes between the three latticed wings.

4. Pteropilium clathrocanium, n. sp. (Pl. [64], fig. 7).

Arachnopilium clathrocanium, Haeckel, Prodromus, 1881, p. 435.

Shell very delicate, with two deep strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 10 : 5. Cephalis subspherical, with circular, polygonally-framed pores, and a central, three-sided pyramidal, apical horn of twice the length. Thorax three-sided pyramidal, with three large, ovate holes between three prominent latticed wings. From its surface arises a very delicate, arachnoidal network with irregular, polygonal meshes, enveloping also the entire cephalis. Abdomen wide and short, as long as the cephalis, and half as broad as the distance of the wings, twice as broad as the constricted mouth.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.04; breadth, a 0.05, b 0.2, c 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 587. Theopodium,[[204]] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent solid ribs, which lie in the wall of the thorax and the abdomen, and are prolonged into three solid terminal feet.

The genus Theopodium and the following closely allied Pterocanium differ from the preceding four genera in the development of the three radial rods or the primary cortinar spines, which are not free lateral wings, but longitudinal ribs enclosed in the wall of the thorax and abdomen, and prolonged over the basal mouth into three free terminal feet. These are solid in Theopodium, which, therefore, corresponds to Lychnocanium among the Dicyrtida.

1. Theopodium tricostatum, n. sp. (Pl. [97], fig. 14).

Shell three-sided pyramidal, thorny, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout conical horn of the same length. Thorax with regular, circular, hexagonally-framed pores. Abdomen with irregular, roundish pores of very different sizes. From the middle part of the thorax arise the three prominent, wing-like edges of the pyramid, which are prolonged over its wide mouth into three stout, pyramidal, divergent feet about as long as the thorax, with dentate, lamellar edges.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.06; breadth, a 0.04, b 0.09, c 0.12.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Theopodium pyramidale, n. sp.

Shell three-sided pyramidal, rough, without external strictures, but with two broad internal girdles. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 8. Cephalis with a thick horn of the same length, conical. Thorax with very small, regular, circular pores. Abdomen with irregular, roundish pores of very different sizes. From the collar stricture arise the three rectilinear edges of the pyramid, which are prolonged over its wide-open mouth into three stout, divergent, pyramidal feet, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.075, c 0.15.

Habitat.—Fossil in Barbados.

Genus 588. Pterocanium,[[205]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent ribs, which run along the thorax and abdomen, and are prolonged into three latticed terminal feet.

The genus Pterocanium differs from the preceding Theopodium in the fenestration of the three terminal feet, which are basal prolongations of the three radial ribs, enclosed in the wall of the thorax and the abdomen. Often also these ribs are partly or wholly fenestrated. It corresponds to Lychnodictyum among the Dicyrtida, and may be derived from this by development of an abdomen. The latter forms sometimes three concave bays, at other times three convex lobes between the three latticed feet.

Subgenus 1. Pterocanarium, Haeckel.

Definition.—Free basal edge of the abdomen between the three feet concave, forming three shallower or deeper bays between them.

1. Pterocanium proserpinæ, Ehrenberg.

Pterocanium proserpinæ, Ehrenberg, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 299, Taf. xi. fig. 22.

Pterocanium proserpinæ, Haeckel, 1862, Monogr. d. Radiol., p. 332.

Shell campanulate, rough. Length of the three joints = 1 : 4 : 2, breadth 1 : 5 : 6. Cephalis subspherical, with a triangular-pyramidal vertical horn of thrice the length. Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal bays. Pores in the thorax and abdomen nearly equal, subregular, circular. Feet from the girdle (or the lumbar stricture) little divergent, nearly straight.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.3, b 0.1, c 0.12.

Habitat.—Mediterranean, Candia, Spratt, depth 1100 fathoms.

2. Pterocanium gravidum, n. sp., (Pl. [73], fig. 3).

Shell campanulate, nearly three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 3, breadth = 1 : 6 : 10. Cephalis subspherical, with a pyramidal straight horn of twice the length. Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal bays; its network prolonged to the ends of the feet. Pores in the thorax and abdomen of nearly equal size, irregular, roundish. Feet from the girdle strongly divergent, with convex back.

Dimensions.—Length of the three joints, a 0.015, b 0.075, c 0.06; breadth, a 0.02, b 0.12, c 0.2.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Pterocanium orcinum, n. sp. (Pl. [73], fig. 2).

Shell campanulate, nearly three-sided pyramidal, covered with conical spines. Length of the three joints = 1 : 4 : 3, breadth = 1 : 5 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax without prominent swellings, with subregular, circular pores. Abdomen shorter, with three concave basal edges and irregular, polygonal pores. Feet from the girdle strongly divergent, nearly straight.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.03, b 0.1, c 0.12.

Habitat.—Central Pacific, Station 263 to 274, depth 2350 to 2925 fathoms.

4. Pterocanium contiguum, Ehrenberg.

Pterocanium contiguum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xvii. fig. 7.

Shell three-sided pyramidal, smooth. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 6. Cephalis small, subspherical, with a large conical horn three times the length. Thorax and abdomen with small, regular, circular pores of equal size, densely crowded together, with thin bars. Abdomen shorter, with three concave basal edges. Feet very thick, straight, from the girdle strongly divergent.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.025; breadth a 0.02, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

5. Pterocanium pyramis, n. sp. (Pl. [68], fig. 7).

Shell three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 3, breadth = 2 : 4 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax campanulate, with fifteen to twenty prominent longitudinal ribs, separating as many rows of regular, circular pores. Abdomen shorter, with three concave basal bays, and irregular, roundish pores. Feet very strong, pyramidal, straight, gradually divergent from the girdle.

Dimensions.—Length of the three joints, a 0.025, b 0.08, c 0.06; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Pterocanium virgineum, n. sp. (Pl. [73], fig. 6).

Shell nearly three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 8, breadth 2 : 6 : 9. Cephalis hemispherical, with a conical straight horn three times the length. Thorax campanulate, with three slight swellings between the three knee-shaped ribs, and with regular circular pores. Abdomen longer, with three concave basal bays, and with very small and numerous pores (much smaller than those of the thorax). At both sides of the three prominent abdominal crests, two rows of larger, nearly square pores occur. Feet slender, nearly straight, divergent.

Dimensions.—Length of the three joints, a 0.15, b 0.06, c 0.12; breadth, a 0.03, b 0.09, c 0.14.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Pterocanium prætextum, Haeckel.

Lychnocanium prætextum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 2.

Shell nearly three-sided prismatic, smooth. Length of the three joints = 1 : 2 : 1, breadth = 1 : 4 : 4. Cephalis subspherical, with a straight, conical horn of three times the length. Thorax campanulate with three slight swellings between the three knee-shaped ribs, and with regular, circular pores. Abdomen smaller, with three deep concave basal bays, and with irregular, roundish pores. Feet longer than the shell, slender, pyramidal, straight, parallel.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Indian Ocean, Ceylon (Haeckel); Zanzibar (Pullen).

8. Pterocanium depressum, Haeckel.

Lychnocanium depressum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 1.

Shell (including the feet) nearly three-sided prismatic, rough. Length of the three joints = 1 : 2 : 1, breadth = 1 : 6 : 6. Cephalis subspherical, with a conical horn of the same length. Thorax a very flat and broad triangular pyramid, three times as broad as long. Abdomen smaller, with three deep, parabolic, concave bays. Pores irregular, roundish. Feet longer than the shell, slender, pyramidal, straight, parallel.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.025, b 0.12, c 0.12.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

9. Pterocanium campanella, Haeckel.

Lychnocanium campanella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 12

Podocyrtis campanella, Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 769.

Shell campanulate, smooth, with three high fenestrated crests and deep collar stricture. Length of the three joints = 1 : 3;1, breadth = 1 : 4 : 3. Cephalis subspherical, with a slender horn of the same length. Thorax inflated, campanulate, with three vaulted swellings between the three curved ribs. Abdomen short, with three semicircular bays between the three feet. Pores of the whole shell regular, circular, small, and numerous. Feet broad, triangular, shorter than the thorax, with convex back and convergent ends.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.2; breadth a 0.02, b 0.08, c 0.07.

Habitat.—Western Tropical Pacific, Philippine Sea, 3300 fathoms (Brooke).

10. Pterocanium tricolpum, n. sp. (Pl. [73], fig. 1).

Shell nearly three-sided prismatic, smooth, with three high fenestrated crests and two deep strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 5 : 5. Cephalis subspherical, with an oblique, conical horn of the same length. Thorax inflated, with three highly vaulted bosoms between the three high crests, and with subregular, circular pores. Abdomen shorter, with three concave (or nearly rectangular, square) basal bays between the three feet, and with irregular, roundish pores, three to four pairs of larger pores occurring at the sides of the base of the feet. Feet nearly as long as the shell, with fenestrated bases, nearly straight and parallel; somewhat convergent, with convex back. (Often the concave bays between the three feet are not square, as in the specimen figured, but semicircular.) The ends of the feet are sometimes strongly convergent. The vaultings of the three swellings and the reticulation are also variable; the whole form is often irregular.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.025, b 0.1, c 0.1.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, surface.

Subgenus 2. Pterocanidium, Haeckel.

Definition.—Free basal edge of the abdomen between the three feet convex, forming three rounded or semicircular prominent lobes between them.

11. Pterocanium eucolpum, n. sp. (Pl. [73], fig. 4).

Dictyopodium eucolpum, Haeckel, 1881, Prodromus et Atlas.

Shell about triangular-prismatic, with two deep strictures, smooth. Length of the three joints = 1 : 3 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with a conical, oblique horn of the same length. Thorax inflated, with three hemispherical swellings between the three crests, and with subregular, hexagonal pores. Abdomen longer, with much smaller, irregular, roundish pores, forming three broad, convex lobes between the three feet. (In the figured specimen the lobes were not fully developed, and extremely thin below the line parallel to the edge. In another specimen, found afterwards in the same locality, the three lobes were much larger, semicircular, and reached almost to the basal plane of the ends of the feet by reason of their convexity.) Feet strong, with slightly convex back, divergent.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.1; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

12. Pterocanium bicorne, n. sp. (Pl. [73], fig. 5).

Dictyopodium bicorne, Haeckel, 1881, Prodromus et Atlas.

Shell nearly three-sided pyramidal, slender, smooth. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 4. Cephalis hemispherical, with two oblique, conical horns of nearly equal length. Thorax nearly hemispherical, with slightly prominent crests, and with subregular, hexagonal pores. Abdomen of about the same length, with much smaller, irregular, roundish pores, forming three convex, nearly circular lobes between the three large divergent feet. These are slender, three-sided pyramidal, longer than the shell, fenestrated at the thickened base, with some rows of larger pores; their back is slightly concave.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.02, b 0.08, c 0.09.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

13. Pterocanium trilobum, Haeckel.

Dictyopodium trilobum, Haeckel, 1882, Monogr. d. Radiol., p. 340, Taf. viii. figs. 6-10.

Shell three-sided pyramidal, nearly tetrahedral, covered with conical spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 6 : 10. Cephalis hemispherical, with a large conical horn (as long as the thorax). Thorax tetrahedral, with little prominent crests. Abdomen forming three semicircular, convex lobes between the three feet, half as long as the thorax, with the same irregular, roundish pores. Feet slender, about as long as the shell, triangular, with convex back, strongly divergent, fenestrated at the inflated and thickened base. (Compare the special description of the living form and its soft body in my Monograph.)

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Mediterranean, Messina, surface.

Genus 589 Pterocodon,[[206]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three solid free lateral wings on the thorax, and numerous solid terminal feet around the mouth of the abdomen.

The genus Pterocodon differs from the closely allied Pterocorys, its ancestral form, in the development of numerous solid feet around the terminal mouth, similar to the terminal corona of Calocyclas.

1. Pterocodon campana, Ehrenberg.

Pterocodon campana, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 10.

Pterocodon campana, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 1.

Shell slender, campanulate, subconical, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 3 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax hemispherical, in the upper part with three divergent, conical horns, as long as the cephalis, and curved downwards. Abdomen with four transverse rows of large circular pores, increasing in size towards the mouth; the largest (undermost), five times as broad as the circular thoracic pores. Mouth not constricted, with a corona of twelve to fifteen divergent, conical feet.

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.06; breadth, a 0.02, b 0.05, c 0.08.

Habitat.—Fossil in Barbados.

2. Pterocodon ornatus, n. sp. (Pl. [70], fig. 11).

Shell nearly ovate, with two deep strictures. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 7. Cephalis hemispherical, with a large oblique horn reaching half the length of the shell; three edges of the horn wing-shaped and dentated. Thorax hemispherical, in the middle zone with three conical wings, which are half as long as the thorax, and curved downwards. Pores hexagonal, roundish, twice as broad in the inflated abdomen as in the thorax. Mouth constricted, with a corona of from fifteen to eighteen conical, divergent, curved feet, similar to the thoracic wings.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.025, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Pterocodon favosus, n. sp.

Shell ovate, with two slight strictures. Length of the three joints = 1 : 2 : 2, breadth = 2 : 4 : 4. Cephalis hemispherical, with a conical horn of twice the length. Three wings of the thorax equal to those of the preceding species. Pores regular, circular, hexagonally framed, of equal size in the thorax and abdomen. Mouth constricted, with a corona of nine straight, conical, nearly vertical feet.

Dimensions.—Length of the three joints, a 0.0025, b 0.05, c 0.05; breadth, a 0.05, b 0.09, c 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 590. Dictyocodon,[[207]] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the thorax, and numerous latticed terminal feet around the mouth of the abdomen.

The genus Dictyocodon, one of the most elegant among the Nassellaria, differs from the preceding Pterocodon in the fenestration of the three lateral wings of the thorax, and the numerous terminal feet of the abdomen. It may be derived from Dictyoceras by development of regular lattice-feet around the terminal mouth.

Subgenus 1. Dictyocodella, Haeckel.

Definition.—The three lateral lattice-wings arise from the thorax alone.

1. Dictyocodon annasethe, n. sp. (Pl. [71], fig. 11).

Shell with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with a very large, three-sided prismatic horn of three times the length, bearing at the base some smaller accessory spines. Thorax nearly conical, with three large, inflated, triangular lattice-wings, the upper edge of which (the cortinar rod) descends obliquely, and is larger than the thorax, ending in a spine. Abdomen inflated, subcylindrical, divided at the wide open mouth by nine deep incisions into nine large triangular feet. Network in the thorax and wings composed of small, regular, hexagonal pores, in the abdomen of three transverse rows of irregular, very large pores, which are surrounded and separated by bands of very small pores; in each foot one large pore and a marginal series of very small pores occur. I dedicate this wonderful species to the memory of my dear wife, Anna Sethe.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.08; breadth, a 0.03, b 0.1, c 0.12.

Habitat.—Indian Ocean; Cocos Islands (Rabbe), surface.

2. Dictyocodon carolotæ, n. sp. (Pl. [71], fig. 14).

Shell with two deep strictures. Length of the three joints = 1 : 3 : 7, breadth = 2 : 5 : 6. Cephalis hemispherical, with an oblique pyramidal horn of twice the length. Thorax subconical, in the upper half with three divergent, triangular wings of half the length, the upper edge of which is nearly horizontal, little curved. Abdomen nearly cylindrical; divided at the wide open mouth by nine deep incisions into nine triangular, vertical feet, about as large as the wings. Network very delicate, with regular, small, circular pores of equal size and very thin bars. I dedicate this elegant species to my dear mother, Charlotte Sethe.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.14; breadth, a 0.04, b 0.1, c 0.12.

Habitat.—Cape of Good Hope (Bleek), surface.

Subgenus 2. Dictyocodoma, Haeckel.

Definition.—The three lateral wings are prolonged from the thorax to the abdomen.

3. Dictyocodon palladius, n. sp. (Pl. [71], figs. 12, 13).

Shell with distinct collar, but evanescent lumbar stricture. Length of the three joints = 1 : 2 : 7, breadth = 1 : 3 : 8. Cephalis very small, with a large pyramidal horn of twice the length, bearing at its base some small, often branched, accessory spines. Thorax three-sided pyramidal, without external boundary prolonged into the large, inflated, gradually dilated abdomen. The internal boundary between the two is marked by a fenestrated, horizontal ring (not indicated in the figure). Three prominent, triangular, fenestrated wings arise from the base of the cephalic horn, and are prolonged nearly through the whole shell almost to the edge of the mouth; in its lower half they form three elevated fenestrated apophyses, the upper edge of which is nearly horizontal. Mouth divided by about twenty incisions into as many triangular, vertical, fenestrated feet. The network of the whole shell is very delicate, like fine gauze, composed of very small, regular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.03, b 0.055, c 0.21; breadth, a 0.03, b 0.09, c 0.25.

Habitat.—Central Pacific, Station 271, surface.

4. Dictyocodon prometheus, n. sp.

Shell tower-shaped, very similar to the preceding species in form and fenestration, but more slender and different in the longer and three-sided prismatic abdomen. Length of the three joints = 1 : 1 : 8, breadth = 1 : 3 : 7. Cephalis with two large divergent horns of three times the length, which are united by interior prolongations with the basal central point, from which arise the upper edges of the three divergent wings; the ends of the latter are directed downwards. Mouth with a corona of about thirty irregular, triangular feet.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.025; breadth, a 0.03, b 0.08, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

Genus 591. Pleuropodium,[[208]] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) without ribs in the thorax, but with three ribs enclosed in the abdomen, which are prolonged into three terminal feet.

The genus Pleuropodium, formerly confounded with Theopodium and Pterocanium, differs from these two closely allied ancestral genera in the localisation of the three lateral ribs, which have disappeared in the thorax and become limited to the abdomen. It is therefore intermediate between the former and the following Podocyrtis.

1. Pleuropodium charybdeum, Haeckel.

Pterocanium charybdeum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 43, Taf. vi. figs. 7-10.

Podocyrtis charybdea, J. Müller, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 492.

Shell campanulate, armed with scattered, bristle-shaped spines, with sharp collar and slight lumbar stricture. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 5. Cephalis cupola-shaped, with a large prismatic, somewhat curved horn, half as long as the shell. Thorax hemispherical, spiny. Abdomen short and wide, three-sided prismatic, with three stout longitudinal ribs, which are prolonged into three slender, prismatic, nearly vertical, slightly curved feet, about as long as the shell. Pores irregular, roundish, of variable size.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Mediterranean (Messina, Nice, &c.), surface.

2. Pleuropodium cortina, n. sp.

Shell campanulate, smooth, with two distinct strictures. Length of the three joints = 1 : 4 : 2, breadth = 1 : 3 : 4. Cephalis subspherical, with a small, pyramidal, straight horn of the same length. Thorax pear-shaped, with regular, circular, hexagonally-framed pores. Abdomen three-sided pyramidal, with irregular, roundish pores and three prominent, stout, prismatic ribs, which are prolonged into three straight, divergent feet of the same length.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth a 0.025, b 0.06, c 0.08.

Habitat.—North Atlantic, Station 354, surface.

Genus 592. Podocyrtis,[[209]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn, which usually is simple.

The genus Podocyrtis, and the two following closely allied genera, differ from all the preceding Theopilida in the absence of lateral ribs or wings, and the possession of three free terminal feet, which arise directly from the peristome, or from the margin of the abdominal mouth. They may be derived from Pleuropodium by reduction and loss of the three piercing lateral ribs, the terminal free prolongations of which only remain. The genus Podocyrtis is one of the largest and most common among all Cyrtoidea, being rich mainly in fossil forms. Ehrenberg in his Polycystins of Barbados (1875, loc. cit., p. 80) enumerated not less than thirty-one species. Some of these are yet living, and occur in the Pacific Radiolarian ooze collected by the Challenger. Other new forms are to be added, so that the number of species described in the following pages amounts to forty-five. Many of these are cosmopolitan, or at least common and widely distributed. To facilitate study we may divide this large genus into four subgenera: in two of these the terminal feet are divergent, or nearly parallel; in the two others convergent. In each of these two groups the pores of the thorax and the abdomen are either nearly equal in size and form, or distinctly different, the abdominal pores being often much larger than the thoracic. The small cephalis bears constantly an apical horn, which is usually simple, rarely branched.

Subgenus 1. Podocyrtarium, Haeckel.

Definition.—Feet divergent (the distance between their ends being greater than that between their bases). Pores of the thorax and abdomen nearly equal in size and similar in form.

1. Podocyrtis tripodiscus, n. sp. (Pl. [72], fig. 4).

Shell nearly conical, gradually dilated from the apical to the basal part, with two slight strictures. Surface a little rough. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 6. Pores subregular, circular, quincuncially disposed, of nearly equal size in the conical thorax and the subspherical abdomen. Cephalis hemispherical, with smaller pores and a spindle-shaped spiny horn of twice the length. Feet cylindrical, as long as the abdomen, little divergent, their ends curved outwards and thickened into a papillate knob.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.08; breadth, a 0.03, b 0.07, c 0.11.

Habitat.—Central Pacific, Station 265 to 272, depth 2425 to 2925 fathoms.

2. Podocyrtis attenuata, Ehrenberg.

Podocyrtis attenuata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 5.

Shell nearly conical, gradually dilated from the apical to the basal part, with two slight strictures. Surface a little rough. Length of the three joints = 2 : 3 : 4, breadth = 2 : 4 : 5. Pores subregular, circular, equal, quincuncial. Cephalis subspherical, with a conical horn of twice the length. Feet cylindrical, as long as the abdomen, little divergent (sometimes as in the specimen figured, nearly parallel).

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.04; breadth, a 0.02, b 0.04, c 0.05.

Habitat.—Fossil in Barbados.

3. Podocyrtis thyrsoceras, n. sp.

Shell slender, conical, smooth, very similar to Thyrsocyrtis rhizodon, Ehrenberg (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 1), with two slight strictures, nearly of the same form and fenestration as in the preceding smaller species. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with a large cylindrical straight horn, which reaches the length of the abdomen, and is papillate in the distal half. Feet cylindrical, divergent, nearly as long as the whole shell, broadened and spinulated at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

4. Podocyrtis conica, n. sp.

Shell conical, without external strictures, but with two internal septal rings. Surface papillate. Length of the three joints = 2 : 3 : 8, breadth = 3 : 6 : 10. Pores equal, subregular, circular, quincuncial. Cephalis hemispherical, with a thick conical horn of the same length. Feet conical, about as long as the thorax, divergent in the direction of the outline of the conical shell.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.08; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Cosmopolitan, Central Pacific, Stations 263 to 274; Tropical Atlantic, Station 348, in depths between 2350 and 2925 fathoms; also fossil in Barbados.

5. Podocyrtis corythæola, n. sp. (Pl. [72], fig. 2).

Shell ovate conical, with two deep strictures, and with rough surface. Length of the three joints = 2 : 5 : 8, breadth = 3 : 8 : 10. Cephalis hemispherical, thorny, with a strong oblique horn three times the length, which is armed with nine to twelve conical spines. Pores small, circular, of irregular size and distribution. Feet spindle-shaped, divergent, as long as the inflated abdomen.

Dimensions.—Length of the three feet, a 0.02, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Indian Ocean, Maldive Islands (Haeckel), surface.

6. Podocyrtis surena, n. sp. (Pl. [72], fig. 10).

Shell thin-walled, tower-shaped, smooth, with two deep strictures. Length of the three joints = 2 : 5 : 10, breadth = 3 : 10 : 11. Cephalis subspherical, with a bent conical horn, as long as the hemispherical thorax. Abdomen cylindrical. Pores subregular, circular, quincuncially disposed, and slightly larger in the abdomen. Feet with a thickened calf, nearly perpendicular, as long as the thorax; their distal ends little divergent, and forming a knob beset with small roundish tubercles.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.035, b 0.1, c 0.11.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

7. Podocyrtis conulus, n. sp.

Shell elongate, conical, rough, without external strictures, but with two internal septal rings. Length of the three joints = 3 : 4 : 15, breadth = 5 : 7 : 12. Cephalis hemispherical, with a thick pyramidal horn of the same length. Feet also pyramidal, divergent, of the same size as the horn. Pores irregular, roundish, of variable size. Abdomen very long.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.15; breadth, a 0.05, b 0.07, c 0.12.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms; also fossil in Barbados.

8. Podocyrtis tridactyla, n. sp.

Shell conical, with two slight strictures, smooth. Length of the three joints = 2 : 6 : 5, breadth = 4 : 5 : 6. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores irregular, polygonal, of variable size. Feet as long as the abdomen, constricted in the middle, trilobed at the distal end; the middle lobe twice as large as the lateral lobes.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.05; breadth, a 0.04, b 0.05, c 0.06.

Habitat.—Indian Ocean, Madagascar, Rabbe.

Subgenus 2. Podocyrtecium, Haeckel.

Definition.—Feet divergent (the distance between their ends being greater than that between their bases). Pores of the thorax and abdomen of different form or size.

9. Podocyrtis prismatica, n. sp. (Pl. [72], fig. 1).

Shell conical, rough, with two distinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 5. Cephalis subspherical, with a curved conical horn of twice the length. Thorax and abdomen together nearly hemispherical. Pores small, regular, circular, quincuncial, twice as large in the abdomen as in the thorax. Feet very large, twice as long as the whole shell, divergent, bent outwards, prismatic, with strong prominent edges.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.06; breadth, a 0.02, b 0.04, c 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

10. Podocyrtis brevipes, Ehrenberg.

Podocyrtis brevipes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 6.

Shell conical, smooth, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 5 : 9. Cephalis subspherical, with a conical horn of the same length. Pores regular, circular, quincuncial, three times as broad in the abdomen as in the thorax. Feet short, triangular, divergent, as long as the horn. (The specimen figured by Ehrenberg was incomplete, one foot and the horn being broken off.)

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.02, b 0.05, c 0.09.

Habitat.—Fossil in Barbados.

11. Podocyrtis divergens, n. sp. (Pl. [72], fig. 6).

Shell slender, subconical, thick-walled, with two distinct strictures. Length of the three joints = 2 : 5 : 7, breadth = 4 : 8 : 10. Cephalis hemispherical, with a large, oblique, prismatic horn three times the length, and a small divergent by-horn at its base. Thorax hemispherical, rough, with regular, circular, quincuncial pores. Abdomen cylindrical, thorny, with larger circular pores of subregular disposition, two to three times as broad as those of the thorax. Feet conical, horn-like, bent, as long as the abdomen; strongly divergent in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.04, b 0.08, c 0.1.

Habitat.—Western Tropical Pacific, Station 220, depth 1100 fathoms.

12. Podocyrtis collaris, Ehrenberg.

Podocyrtis collaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 1.

Shell conical, with slight collar and deeper lumbar stricture. Length of the three joints = 1 : 4 : 4, breadth = 1 : 4 : 8. Cephalis hemispherical, with a small oblique horn of the same length. Pores regular, circular, quincuncial, four to six times as broad in the inflated abdomen as in the conical thorax. Feet short and slightly divergent, little longer than the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.08; breadth, a 0.03, b 0.08, c 0.16.

Habitat.—Fossil in Barbados.

13. Podocyrtis ventricosa, Ehrenberg.

Podocyrtis ventricosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 3.

Shell conical, with two deep strictures, thorny. Length of the three joints = 1 : 2 : 5, breadth = 1 : 4 : 8. Cephalis subspherical, with a small conical horn of the same length. Pores regular circular, quincuncial, four to six times as broad in the inflated abdomen as in the hemispherical thorax. (Pores much larger and less numerous than in the similar preceding species.) Feet broad and stout, triangular, divergent, as long as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.025, b 0.07, c 0.16.

Habitat.—Fossil in Barbados.

14. Podocyrtis flosculata, n. sp. (Pl. [72], fig. 9).

Shell conical, rough, as broad as long, with distinct collar, but obliterated lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 7. Cephalis hemispherical, with a thick conical horn of the same length. Thorax truncate, conical, with small, circular, quincuncial pores. Abdomen inflated, with very large and remarkable regular, quincuncial pores; their inner edge circular, the outer six-lobed, the six lobes elegantly alternating with six short conical spines. Feet very coarse, equilateral triangular, half as broad as the thorax, little divergent.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

15. Podocyrtis centriscus, Ehrenberg.

Podocyrtis centriscus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xiv. fig. 2.

Shell conical, rough, about as high as broad, with two obliterated strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 7. Cephalis small, hemispherical, with a stout conical horn. Pores of the inflated abdomen irregular, roundish, very large, three occurring in the course of its length, five times as broad as the small, very numerous, regular, circular pores of the conical thorax. Feet S-shaped, as long as the abdomen, with the blunt end curved outwards.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

16. Podocyrtis magnifica, n. sp. (Pl. [72], fig. 5).

Shell conical, spiny, a little longer than broad, with two distinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 4 : 7. Cephalis hemispherical, with a large conical horn, which is as long as the abdomen, nearly scaly, and covered with short, simple, and bifid spines. Pores regular, circular, quincuncially disposed, four times as broad in the inflated abdomen as in the conical thorax. Spines of the former twice as large as those of the latter. Feet very long and slender, cylindrical, S-shaped, bent outwards at the thickened distal end, with a spindle-shaped papillate knob.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Canary Islands, Lanzerote, Haeckel, surface.

17. Podocyrtis princeps, Ehrenberg.

Podocyrtis princeps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 1.

Podocyrtis princeps, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 32.

Shell conical, with two distinct strictures. Length of three joints = 1 : 2 : 5, breadth = 1 : 4 : 7. Cephalis subspherical, with a large cylindrical, vertical horn, longer than the whole shell. Pores regular, circular, quincuncial, in the inflated spiny abdomen very large (four to five in the course of its length), five times as broad as in the smooth conical thorax. Feet about as long as the shell, slightly bent, S-shaped, cylindrical.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.14.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; fossil in Barbados.

18. Podocyrtis euceros, Ehrenberg.

Podocyrtis euceros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 1.

Shell conical, campanulate, with two deep strictures. Length of the three joints = 1 : 3 : 6, breadth = 2 : 5 : 7. Cephalis hemispherical, with a large, cylindrical horn, nearly as long as the shell. Pores regular, circular, hexagonally framed, quincuncial, four times as broad in the papillated, inflated abdomen as in the hemispherical, smooth thorax. Feet short and broad, triangular, divergent, about as long as the thorax. (In the specimen figured by Ehrenberg, two feet were broken off).

Dimensions.—Length of the three joints, a 0.016, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, and Pacific Oceans, at many stations, and in various depths; fossil in Barbados.

19. Podocyrtis cristata, n. sp. (Pl. [72], fig. 7).

Shell conical-campanulate, thorny, with two deep strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 4 : 7. Cephalis subspherical, with a large, oblique, little bent, conical horn, as long as the abdomen. Thorax hemispherical, papillate, with small, regular, circular pores. Abdomen inflated, with very large, circular pores, (three to four in its length), six times as broad as those of the thorax, and separated by hexagonal, serrated crests. Feet cylindrical, stout, S-shaped, slightly divergent, with a spherical papillate knob at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.035, b 0.07, c 0.14.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

20. Podocyrtis schomburgkii, Ehrenberg.

Podocyrtis schomburgkii, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 22; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xiv. 7.

Shell ovate-conical, with two distinct strictures. Length of the three joints = 2 : 5 : 10, breadth = 3 : 8 : 12. Cephalis hemispherical, with a large, straight, conical horn as long as the abdomen. Thorax campanulate, smooth, with small, regular, circular pores. Abdomen inflated, papillate, with very large, regular, hexagonal pores (three to four in the course of its length), five times as broad as their bars and as the pores of the thorax. Feet as long as the abdomen, nearly parallel, slightly bent outwards at the conical distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

21. Podocyrtis hexagonalis, n. sp.

Shell nearly ovate, slender, everywhere covered with a regular network of high, hexagonal, denticulated crests, separating the circular, funnel-shaped pores, which are twice as large in the subspherical abdomen as in the hemispherical thorax, between both of which are two deep strictures. Length of the three joints = 1 : 3 : 6, breadth = 2 : 5 : 6. Cephalis hemispherical, with a long and thin cylindrical, vertical horn, as long as the abdomen. Feet of the same length and form, nearly straight, slightly divergent.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.04, b 0.11, c 0.13.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

22. Podocyrtis ovata, n. sp.

Shell nearly ovate, papillate, without external strictures. Length of the three joints = 1 : 2 : 3, breadth = 2 : 4 : 5. Cephalis hemispherical, with a pyramidal horn half as long as the shell. Pores regular, circular, hexagonally framed, three times as broad in the inflated abdomen as in the conical thorax. Feet pyramidal, little bent, divergent, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.08; breadth, a 0.05, b 0.095, c 0.12.

Habitat.—Mediterranean, Corfu, Haeckel, surface.

23. Podocyrtis urceolata, n. sp.

? Podocyrtis mitra, Bury, 1862, Polycystins of Barbados, pl. v. fig. 3.

Shell nearly ovate, smooth, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 5. Cephalis subspherical, with a stout, conical horn of the same length. Thorax flat, hemispherical, with four to six transverse rows of small circular pores. Abdomen urceolate, with four to five transverse rows of very large, subregular, hexagonal pores. Feet short and thick, bent outwards, as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.15; breadth, a 0.05, b 0.1, c 0.13.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; fossil in Barbados.

24. Podocyrtis ehrenbergii, Haeckel.

Podocyrtis amphiacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvii. fig. 3.

Shell slender, ovate, smooth, with deep collar, but evanescent lumbar stricture. Length of the three joints = 1 : 3 : 2, breadth = 1 : 3 : 3. Cephalis subspherical, with a large conical horn, as long as the campanulate thorax. Abdomen nearly cylindrical. Pores irregular, roundish, two to four times as large in the abdomen as in the thorax. Feet conical, slender, divergent, nearly as long as the shell. (In the imperfect specimen figured by Ehrenberg, two spines were broken off.)

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms; fossil in Barbados.

25. Podocyrtis argulus, Ehrenberg.

Podocyrtis argulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 2.

Shell slender, ovate, or subconical, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 4. Cephalis hemispherical, with a small conical horn of the same length (broken off in the figure of Ehrenberg). Pores regular, circular, three times as broad in the inflated abdomen as in the campanulate thorax. Feet spindle-shaped, slender, divergent, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.1; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—Tropical Atlantic, Station 247, depth 2530 fathoms; also fossil in Barbados.

Subgenus 3. Podocyrtidium, Haeckel.

Definition.—Feet convergent (the distance between their ends being smaller than that between their bases). Pores of the thorax and abdomen nearly equal in size and similar in form.

26. Podocyrtis papalis, Ehrenberg.

Podocyrtis papalis, Ehrenberg, Mikrogeol., Taf. xxxvi. fig. 23; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xv. fig. 6.

Shell ovate, smooth, without external stricture. Length of the three joints = 1 : 3 : 1, breadth = 1 : 3 : 3. Cephalis ovate, with a stout pyramidal horn of twice the length. Thorax and abdomen with about thirty longitudinal, divergent ribs, separating the same number of longitudinal rows of regular, circular pores, the size of which increases gradually towards the base. Feet shovel-shaped (broad, triangular, with convex outer and concave inner side, the obtuse end being curved inwards), about as long as the short abdomen, only slightly convergent.

Dimensions.—Length of the three joints, a 0.04, b 0.12, c 0.04; breadth, a 0.04, b 0.12, c 0.11.

Habitat.—Fossil in Barbados.

27. Podocyrtis costata, n. sp.

Shell ovate, smooth, of the same form and structure as Podocyrtis papalis, but with two distinct strictures and different proportions. Length of the three joints = 1 : 3 : 6, breadth = 2 : 4 : 6. About thirty longitudinal ribs regularly alternating with rows of circular, regular pores. Feet as in Podocyrtis papalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

28. Podocyrtis mitrella, Ehrenberg.

Podocyrtis mitrella, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 3.

Shell ovate, smooth, nearly of the same form and structure as Podocyrtis papalis, but different in the proportions of the joints, in the much smaller, regular pores, and in the great breadth of the shovel-shaped, blunt, about semicircular feet. Length of the three joints = 2 : 9 : 4, breadth = 3 : 10 : 3. Cephalis subspherical, with a thick pyramidal horn of the same length. Slight collar, but no lumbar stricture.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.04; breadth, a 0.03, b 0.1, c 0.03.

Habitat.—Fossil in Barbados.

29. Podocyrtis mitra, Ehrenberg.

Podocyrtis mitra, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 20; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xv. fig. 4.

Shell ovate, conical, smooth, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis with the horn (of equal length) conical. Pores regular, circular, in about twenty longitudinal rows, slightly increasing in size in the middle part of the abdomen. Feet shovel-shaped, blunt, slightly divergent, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.5, c 0.7; breadth, a 0.03, b 0.075, c 0.1.

Habitat.—Cosmopolitan; Mediterranean (Gibraltar), Canary Islands, Central Pacific, Stations 265 to 274, in different depths; also fossil in Barbados.

30. Podocyrtis argus, Ehrenberg.

Podocyrtis argus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 9.

Shell ovate, with two distinct strictures, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subconical, with a conical horn of the same length. Thorax campanulate. Abdomen inflated. Pores subregular, roundish, of nearly equal breadth, quincuncial. Feet shovel-shaped, triangular, nearly vertical, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.025, b 0.08, c 0.1.

Habitat.—Tropical Atlantic, Station 347, surface; fossil in Barbados.

31. Podocyrtis eulophos, Ehrenberg.

Podocyrtis eulophos, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 6.

Shell subconical, slender, with two slight strictures, smooth. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 6. Cephalis hemispherical, with a large, spindle-shaped, angular horn of twice the length. Thorax hemispherical. Abdomen truncate, conical. Pores subregular, roundish, in about twenty longitudinal rows, their breadth gradually increasing towards the base. Feet shovel-shaped, blunt, nearly vertical, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.16; breadth, a 0.05, b 0.08, c 0.14.

Habitat.—Fossil in Barbados.

32. Podocyrtis favosa, n. sp.

Shell ovate, with two slight strictures, and with honeycomb-like surface. Length of the three joints = 1 : 5 : 2, breadth = 2 : 6 : 5. Cephalis hemispherical, with a pyramidal horn of twice the length. Thorax hemispherical. Pores regular, circular, hexagonally framed, funnel-shaped, with high, prominent crests between them. Feet shovel-shaped, little convergent, triangular, as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.04; breadth, a 0.04, b 0.12, c 0.11.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

33. Podocyrtis fusiformis, n. sp.

Shell slender, nearly spindle-shaped, diminishing gradually from the broadest middle part (immediately above the lumbar septum) towards the two poles. Length of the three joints = 1 : 5 : 8, breadth = 2 : 6 : 5. Cephalis subspherical, with a large conical horn three times the length. Thorax and abdomen with twenty-four to thirty denticulated, longitudinal ribs, separating the same number of longitudinal rows of regular, circular pores. Instead of the lumbar stricture, a broad, internal septum occurs. Feet slender, straight, as long as the abdomen, only slightly convergent.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.16; breadth, a 0.05, b 0.12, c 0.1.

Habitat.—Indian Ocean, Madagascar (Rabbe) surface.

Subgenus 4. Podocyrtonium, Haeckel.

Definition.—Feet convergent (the distance between their ends being smaller than that between their bases). Pores of the thorax and abdomen different in size or form.

34. Podocyrtis pedicellaria, n. sp. (Pl. [72], fig. 8).

Shell conical, ovate, with two very slight strictures. Length of the three joints = 2 : 3 : 8, breadth = 2 : 4 : 8. Cephalis conical, with a pyramidal horn of the same length. Pores subregular, circular, quincuncially disposed, two to three times as broad in the smooth abdomen as in the rough, spinulate thorax. Feet as long as the thorax, shovel-shaped (broad, triangular, with convex outer and concave inner side, the free ends being curved inwards), only slightly convergent.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.16; breadth, a 0.05, b 0.09, c 0.16.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

35. Podocyrtis sinuosa, Ehrenberg.

Podocyrtis sinuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 5.

Podocyrtis sinuosa, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 33.

Shell slender, conical, with slight collar, but without lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 4. Cephalis subspherical (in the figure of Ehrenberg broken off), with a pyramidal horn of the same length. Pores subregular, circular, four times as broad in the abdomen as in the thorax. Feet shovel-shaped, as long as the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—Fossil in Barbados.

36. Podocyrtis floribunda, n. sp.

Shell ovate, conical, with two very slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 4 : 7. Between twenty-four to thirty longitudinal, denticulated ribs lie the same number of subregular pores, which are flower-like, lobed, or rosette-shaped, and two to three times as large in the abdomen as in the thorax. Feet shovel-shaped (as in the similar Podocyrtis pedicellaria (Pl. [72], fig. 8).

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms; also fossil in Barbados.

37. Podocyrtis scaphopodia, n. sp.

Shell conical, rough, with two slight strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 4 : 8. Cephalis subspherical, with a pyramidal horn of twice the length. Pores subregular, circular, quincuncial, four times as large in the abdomen as in the thorax. Feet short and broad, triangular, shovel-shaped, with convergent ends. This species is similar to Podocyrtis brevipes, but differs in the form and size of the horn and of the feet.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.05; breadth, a 0.02, b 0.04, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

38. Podocyrtis lithoconus, n. sp. (Pl. [72], fig. 3).

Shell conical, thick-walled, smooth, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 4 : 7. Cephalis hemispherical, with a spindle-shaped horn of the some length. Pores subregular, circular, two to four times as broad in the abdomen as in the thorax. Feet triangular, shovel-shaped, nearly vertical, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

39. Podocyrtis ampla, Ehrenberg.

Podocyrtis ampla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 7.

Shell conical, thick-walled, with distinct collar, but without lumbar stricture. Length of the three joints = 1 : 4 : 5, breadth = 1 : 6 : 7. Cephalis hemispherical, with a large conical horn, as long as the thorax. Pores regular, circular, quincuncial, three times as broad in the rough abdomen as in the smooth thorax. Feet very small, shovel-shaped, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.14.

Habitat.—North Atlantic (Florida); also fossil in Barbados.

40. Podocyrtis nana, Ehrenberg.

Podocyrtis nana, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 2.

Shell conical, thorny, with two distinct strictures. Length of the three joints = 1 : 3 : 3, breadth = 2 : 5 : 6. Cephalis hemispherical, with a large cylindrical horn, nearly as long as the shell. Pores in the abdomen irregular, roundish, two to four times as broad as the regular, circular, quincuncial pores of the thorax. Feet very small, shovel shaped, scarcely as long as the cephalis.

Dimensions.—Length of the three joints, a 0.01, b 0.03, c 0.03; breadth, a 0.02, b 0.05, c 0.06.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms; also fossil in Barbados.

41. Podocyrtis lyæa, Haeckel.

Thyrsocyrtis lyæa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii, fig. 3.

Shell ovate, conical, with two deep strictures. Length of the three joints = 2 : 5 : 8, breadth = 3 : 8 : 9. Cephalis hemispherical, with a large conical horn, which is spinulate, scaly, and as long as the abdomen. Pores subregular, circular, two to four times as broad in the smooth abdomen as in the spiny thorax. Feet very short and broad, shovel-shaped, scarcely as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

42. Podocyrtis bromia, Haeckel.

Thyrsocyrtis bromia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 2.

Shell ovate, thorny, with two distinct strictures. Length of the three joints = 2 : 5 : 5, breadth = 3 : 8 : 9. Cephalis subspherical, with a large conical horn, which is half as long as the shell, and spirally dentated in the distal half. Thorax conical, spinulate, with regular, circular, quincuncial pores. Abdomen tuberculate, with a small number of very large irregular pores. Feet short, shovel-shaped, nearly vertical, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.05; breadth, a 0.03, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

43. Podocyrtis sphærogaster, n. sp.

Shell inversely ovate, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 7. Cephalis hemispherical, with a slender, slightly bent horn, as long as the abdomen. Thorax hemispherical, spinulate. Abdomen nearly spherical, with much constricted mouth. Pores subregular, circular, hexagonally framed. Feet slender, cylindro-conical, about as long as the shell, with outer convexity, distinctly convergent.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

44. Podocyrtis tripus, Haeckel.

Podocyrtis bicornis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 8.

? Podocyrtis dipus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 83, Taf. xii. Fig. 11.

Shell conical, rough, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 5. Cephalis subspherical, with a large, oblique, conical horn (sometimes with a small accessory horn at its base). Thorax hemispherical, with subregular, circular, small, quincuncial pores. Abdomen campanulate, with a small number (about twenty) of very large, irregular, polygonal pores. Feet conical, small, as long as the thorax, slightly convergent or nearly vertical.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

45. Podocyrtis triacantha, Ehrenberg.

Podocyrtis triacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xiii. fig. 4.

Shell conical, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 6. Cephalis hemispherical, with a very large conical horn, nearly as long as the whole shell. Thorax campanulate, densely spinulate, with very small, regular, circular, quincuncial pores. Thorax inflated, with very large, irregular, roundish, pores (three to four in the course of its length), five to ten times as broad as those of the thorax. Feet slender and thin, subcylindrical, as long as the abdomen, divergent in the proximal half, convergent and curved inwards in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

Genus 593. Thyrsocyrtis,[[210]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three branched terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn, which usually bears lateral spines.

The genus Thyrsocyrtis differs from the preceding Podocyrtis, its ancestral form, in the ramification of the three terminal feet, which in the latter genus remain simple.

1. Thyrsocyrtis rhizodon, Ehrenberg.

Thyrsocyrtis rhizodon, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xii. fig. 1.

Shell slender, conical, smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a large cylindrical horn, reaching half the length of the shell, and papillate in the distal half. Pores nearly equal, regular, circular, quincuncially disposed, small. Feet divergent, about half as long as the shell, broadened and forked at the distal end. (The fork incision is often much deeper, as in the figure given by Ehrenberg.)

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.03, b 0.06, c 0.08.

Habitat.—Fossil in Barbados.

2. Thyrsocyrtis arborescens, n. sp. (Pl. [68], fig. 9).

Shell nearly ovate, thorny, with a deep collar, but without lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 2 : 3 : 4. Cephalis hemispherical, with a stout scaly or branched horn, half as long as the shell. Pores irregular, roundish, small, separated by spinulated crests, of slightly different sizes. Feet divergent, cylindrical, and as long as the thorax in the proximal half, irregularly branched or arborescent in the distal half, with ten to thirty blunt, thickened or papillate, terminal branches.

Dimensions.—Length of three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.04, b 0.06, c 0.08.

Habitat.—Central Pacific, Station 268, depth, 2900 fathoms.

3. Thyrsocyrtis furcata, n. sp.

Shell ovate, thorny, with two slight strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 3. Cephalis hemispherical, with a pyramidal smooth horn of twice the length. Pores of the thorax and abdomen nearly equal, regular, circular, quincuncial. Feet very broad, forked, about as long as the abdomen, much divergent; the outer fork-branch as long as the simple basal half of the foot, and twice as long as the inner or axial branch.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.09; breadth, a 0.04, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

4. Thyrsocyrtis rhizopus, Haeckel.

Podocyrtis rhizodon, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 83, Taf. xv. fig. 2.

Shell pear-shaped, smooth, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 5. Cephalis ovate, with a stout, sword-shaped horn of the same length. Pores regular, circular, twice as broad in the inflated abdomen as in the truncate, conical thorax. Feet cylindrical, parallel, vertical, straight, divided at the distal end into two short fork-branches.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

5. Thyrsocyrtis rhizopodium, n. sp. (Pl. [68], fig. 8).

Shell campanulate-conical, with deep collar, but without lumbar stricture. Length of the three joints = 3 : 4 : 10, breadth = 4 : 10 : 15. Cephalis subspherical, with a small conical horn of the same length. Pores regular, circular, quincuncial, three to four times as large in the inflated abdomen as in the truncate, conical thorax. Feet cylindrical, slightly divergent, about as long as the abdomen, S-shaped, bent outwards, irregularly branched in the distal half, with tuberculate terminal branches.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.1, c 0.15.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Thyrsocyrtis radicata, Haeckel.

Podocyrtis radicata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 5.

Shell campanulate-conical, with two distinct strictures, length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 6. Cephalis subspherical, with a small conical horn of half the length. Pores regular, circular, quincuncial, four to five times as broad in the inflated, rough abdomen as in the campanulate, smooth thorax. Feet cylindrical, nearly as long as the whole shell, S-shaped, bent outwards, dilated and hand-shaped at the distal end, divided by three to five incisions in some irregular finger-like branches.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth a 0.03, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

7. Thyrsocyrtis trifida, n. sp.

Shell campanulate-conical, thorny, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis subspherical, with a short pyramidal horn of the same length. Pores regular, circular, hexagonally framed, twice as broad in the inflated spiny abdomen as in the rough, campanulate thorax. Feet very large, as long as the shell, cylindrical in the proximal simple half, in the distal half broadened and cleft into three large, irregularly lobed branches, two shorter lateral, and one longer abaxial branch; the latter forms the prolongation of the proximal half. The outer straight edges of the three diverging feet correspond to the edges of a three-sided pyramid.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.09, c 0.15.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 594. Dictyopodium,[[211]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn.

The genus Dictyopodium differs from the two preceding ancestral genera in the fenestration of the three terminal feet, which in Podocyrtis are simple, in Thyrsocyrtis branched, but not latticed.

1. Dictyopodium eurylophus, Ehrenberg.

Dictyopodium eurylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 4.

Shell campanulate-conical, thorny, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout angular horn of twice the length, which at the apex is broadened and divided into some spines. Pores in the hemispherical thorax and in the truncate, conical abdomen of nearly equal size, small, subregular, circular (in the abdomen sometimes more irregular and unequal). Feet as long as the abdomen, arising from it with triangular base, diverging, fenestrated throughout the entire length.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms; fossil in Barbados.

2. Dictyopodium oxylophus, Ehrenberg.

Dictyopodium oxylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 5.

Shell subconical, smooth, with two slight strictures. Length of the three joints = 2 : 5 : 7, breadth = 3 : 8 : 10. Cephalis subspherical, with a small, conical, smooth horn of the same length. Pores irregular, polygonal, roundish, slightly larger in the abdomen than in the thorax. Feet as long as the thorax, arising from it with triangular base, diverging, fenestrated throughout the entire length. (The figures of this and the preceding species given by Ehrenberg are incomplete, having been drawn from spoiled specimens. In perfect specimens all the three feet are present and diverge in both species in the direction of the conical outline. The main difference between the two species is connected with the pores, which in Dictyopodium oxylophus are larger and more irregular, the two strictures are here not so deep.)

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Fossil in Barbados.

3. Dictyopodium scaphopodium, n. sp. (Pl. [73], fig. 8).

Shell campanulate, conical, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 1 : 4 : 8. Cephalis hemispherical, with a conical, smooth horn of twice the length. Thorax hemispherical, rough, with small, regular, circular pores. Abdomen inflated and papillate, with very large, polygonal or roundish pores (eight to ten times as broad as the thoracic pores). Feet divergent, nearly as long as the shell, S-shaped, bent outwards, solid and cylindrical in the proximal half, shovel-shaped and fenestrated in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.025, b 0.08, c 0.16.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Dictyopodium cothurnatum, Haeckel.

Podocyrtis cothurnata, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. B. 21; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xiv. fig. 1.

Anthocyrtis cothurnata, Haeckel, 1862, Monogr. d. Radiol., p. 310.

Shell subconical, rough, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis hemispherical, with a very large cylindrical, vertical horn, about as long as the whole shell. Thorax conical, rough, with small, regular, circular pores. Abdomen inflated, with very large, roundish pores (four to five in the course of its length), six to eight times as large as the thoracic pores. Feet nearly vertical, only slightly divergent, S-shaped, bent, as long as the abdomen, cylindrical; at the distal end shovel-shaped and fenestrated (often much more than in Ehrenberg's figure).

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.1; breadth, a 0.03, b 0.09, c 0.15.

Habitat.—Fossil in Barbados.

5. Dictyopodium thyrsolophus, n. sp. (Pl. [73], fig. 7).

Shell subconical, rough, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with an elegant horn, which is half as long as the shell, spindle-shaped and scaly on the distal third. Thorax hemispherical, with small, regular, circular pores. Abdomen inflated, papillate, with regular, circular pores, three times as large as the thoracic pores (five to six in the course of its length). Feet slightly divergent, cylindrical, about as long as the shell, shovel-shaped and fenestrated (with a prominent middle rib) at the distal end.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.1, c 0.18.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subfamily 2. Theoperida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Podocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida triradiata clausa).

Genus 595. Lithornithium,[[212]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three solid lateral wings on the thorax.

The genus Lithornithium has an ovate or spindle-shaped shell, with two distinct strictures, and tapering towards both poles. The abdomen is simple, whilst the cephalis bears an apical horn, and the thorax three free, lateral, solid, divergent wings. It may be derived from Pterocorys by development of a terminal lattice-plate closing the mouth.

1. Lithornithium ciconia, n. sp. (Pl. [67], fig. 3).

Shell nearly spindle-shaped, with two indistinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a large pyramidal spine of twice the length. Thorax three-sided pyramidal with three pyramidal wings of the same length, the broad triangular bases of which occupy the whole length of the thoracic edges. Abdomen inversely ovate (in the figured specimen broken off, in another specimen, found afterwards, completely closed at the distal end). Pores very small, regular, circular, of equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Lithornithium falco, n. sp. (Pl. [67], fig. 1).

Shell nearly ovate, with two sharp strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 3. Cephalis hemispherical, with a conical spine of the same length. Thorax subspherical, with three conical wings of half the length, little curved, arising with broad triangular base from the upper half of the thorax. Abdomen inversely conical. Pores irregular, roundish, of different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.07; breadth, a 0.03, b 0.08, c 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Lithornithium trochilus, n. sp. (Pl. [67], fig. 4).

Shell nearly spindle-shaped, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 2. Cephalis hemispherical, with a thin curved horn of the same length. Cephalis subovate, with three thin curved wings of half the length, arising with broad base from its upper half. Abdomen ovate. Pores subregular, circular, of slightly different sizes.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.06; breadth, a 0.02, b 0.05, c 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Lithornithium foveolatum, Ehrenberg.

Lithornithium foveolatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 7.

Shell subovate, with two distinct strictures. Length of the three joints = 2 : 4 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with a short conical spine of the same length. Thorax subspherical, with three broad triangular wings of half the length arising from its lower half. Abdomen subconical. Pores small, regular, circular, of nearly equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.03; breadth, a 0.03, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

5. Lithornithium fringilla, n. sp. (Pl. [67], fig. 2).

Shell ovate, with two slight strictures. Length of the three joints = 4 : 7 : 4, breadth = 3 : 7 : 5. Cephalis ovate, with a pyramidal spine of the same length Thorax subconical, with three stout conical, curved wings of half the length, arising from its lower third (immediately above the girdle). Abdomen inversely campanulate. Pores subregular, circular, of equal size.

Dimensions.—Length of the three joints, a 0.04, b 0.07, c 0.04; breadth, a 0.03, b 0.07, c 0.05.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Lithornithium hirundo, Ehrenberg.

Lithocampe hirundo, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 65.

Lithornithium hirundo, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 53.

Shell nearly ovate, with two deep strictures. Length of the three joints = 2 : 6 : 4, breadth = 2 : 7 : 5. Cephalis hemispherical, with an oblique, conical horn of twice the length. Thorax hemispherical, with three long, angular, little divergent wings of twice the length, which are S-shaped, curved, and arise from its lower third, immediately above the girdle. Abdomen inversely conical. Pores irregular, roundish, of different sizes. In the figure of Ehrenberg the abdomen is broken off; in a specimen from Caltanisetta, with somewhat shorter and broader wings, I found it complete.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.07, c 0.05.

Habitat.—Fossil in Tertiary rocks of the Mediterranean (Ægina, Greece; Caltanisetta, Sicily).

Genus 596. Sethornithium,[[213]] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three latticed lateral wings on the thorax.

The genus Sethornithium differs from the preceding Lithornithium, its ancestral form, only in the fenestration of the three thoracic wings, and bears therefore to it the same relation that Dictyoceras exhibits to Pterocorys.

1. Sethornithium dictyopterum, n. sp. Pl. [68], fig. 14.

Shell ovate, with two slight strictures. Length of the three joints = 2 : 4 : 3, breadth = 1 : 5 : 4. Cephalis ovate, with a pyramidal horn of twice the length. From the middle part of the thorax arise three broad, triangular, latticed wings of about the same length, the distal end of each of which is curved downwards. Abdomen inversely conical. Pores regular, circular. (Similar to Lithornithium fringilla, Pl. [67], fig. 2, but with much larger wings, which in the greater part are fenestrated.)

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.06; breadth, a 0.02, b 0.1, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 597. Theopera,[[214]] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three lateral wings, beginning from the sides of the thorax and prolonged into the sides of the abdomen.

The genus Theopera differs from the two preceding genera in the greater extension of the three lateral wings, which are prolonged from their original base, the thorax, into the inversely conical abdomen. It has therefore an intermediate position between the preceding and the following genera. It differs from the similar Pterocanium and Theopodium in the closure of the constricted and fenestrated mouth.

1. Theopera prismatica, n. sp. (Pl. [67], fig. 7).

Rhopalocanium prismaticum, Haeckel, 1879, Atlas, pl. lxvii. fig. 7.

Shell three-sided prismatic, with three broad and long hyaline wings, which are prolonged from the collar stricture almost to the basal end, with three parallel edges. Length of the three joints = 2 : 8 : 10, breadth = 3 : 9 : 8. Cephalis hemispherical, with a conical horn of the same length. Thorax subspherical; abdomen inversely ovate; pores of both small, regular, circular, of equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—South Atlantic, Station 332. depth 2200 fathoms.

2. Theopera pyramis, Haeckel.

Rhopalocanium sp., Bury, 1862, Polycystins of Barbados, pl. xvii. fig. 8.

Shell three-sided pyramidal, with three broad and long hyaline wings, which are prolonged from the collar stricture almost to the basal end, with three diverging edges. Length of the three joints = 3 : 8 : 11, breadth = 4 : 8 : 9. Cephalis subspherical, with a conical horn of the same length. Thorax hemispherical; abdomen inversely campanulate. Pores in the abdomen twice to three times as broad as in the thorax, subregular, circular. Differs from the preceding species mainly in the broader pyramidal form and the divergence of the wings.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.11; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

3. Theopera fusiformis (Pl. [67], fig. 5).

Shell nearly spindle-shaped, rough, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 5 : 4. Cephalis hemispherical, large, with an oblique conical horn of the same length. Thorax hemispherical; abdomen inversely conical. Pores irregular, roundish, of very different sizes. Three wings short, broad, diverging, triangular, and striated, embracing at the base the lumbar stricture, the lower third of the thorax and the upper third of the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.12; breadth, a 0.045, b 0.1, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

4. Theopera luscinia, Haeckel.

Lithornithium luscinia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 9.

Shell slenderly ovate, with distinct collar, but indistinct lumbar strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 5 : 5. Cephalis hemispherical, with a slender cylindrical horn of three times the length, bearing a spindle-shaped spinulate top (like a fir-cone). Pores subregular, circular, twice as broad in the abdomen as in the thorax. Three wings arising with broad triangular base, embracing the lower third of the thorax and the upper third of the abdomen, prolonged into three slender diverging spines, as long as the shell.

Dimensions.—Length of the three joints a 0.015, b 0.05, c 0.1; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Fossil in Barbados.

5. Theopera chytropus, n. sp. (Pl. [67], fig. 6).

Shell slender, ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 1 : 2 : 5, breadth = 1 : 3 : 3. Cephalis hemispherical, with a conical horn of the same length. Pores in the thorax and abdomen of similar shape, irregular, roundish. Three wings with broad triangular base attached at the upper half of the shell, in the lower half free, diverging, with a spinulate knob at the distal end.

Dimensions.—Length of the three joints, a 0.025, b 0.06, c 0.15; breadth, a 0.03, b 0.09, c 0.09.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

6. Theopera cortina, n. sp. (Pl. [67], fig. 8).

Shell slender, ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 1 : 2 : 6, breadth 1 : 4 : 4. Cephalis subspherical, with an elegant pyramidal horn of three times the length, bearing an ovate, spinulate knob. Pores subregular, circular, two or three times as large in the abdomen as in the thorax. The three wings are slightly elevated small ribs on the thorax, arise with broad, triangular, striated bases in the upper half of the abdomen, and are prolonged into three slender diverging feet, which are as long as the shell, and bear a spinulate, ovate knob at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.13; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

Genus 598. Rhopalocanium,[[215]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three lateral wings on the sides of the inversely conical abdomen, which bears no vertical terminal horn on the basal apex.

The genus Rhopalocanium, and the closely allied Rhopalatractus which follows, differ from the preceding Theopera, their probable ancestral form, in the origin of the three lateral wings from the inversely conical abdomen, the thorax bearing no wings. The upper part of the wing bases, which arose formerly from the thorax, is here reduced and lost.

1. Rhopalocanium lasanum, n. sp. (Pl. [67], fig. 10).

Shell subovate, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a conical, dimpled horn of twice the length. Thorax subconical, abdomen campanulate, both with irregular, circular pores. Three wings cylindrical, divergent, about as long as the shell, striated, with an ovate, dimpled knob at the distal end, their broad triangular base being attached to the upper half of the abdomen. (Form rather variable.)

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.09; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 3000 fathoms.

2. Rhopalocanium ornatum, Ehrenberg.

Rhopalocanium ornatum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 9; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xvii. fig. 8.

Shell nearly spindle-shaped, with two distinct strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 3. Cephalis hemispherical, with a stout, cylindrical horn of twice the length, bearing a dimpled cone. Thorax ovate, campanulate. Abdomen inversely conical. Pores subregular, circular, twice as large in the thorax as in the abdomen. Three wings compressed, slender, divergent, slightly longer than the abdomen, bearing an ovate, dimpled cone at their distal end, with the broad, triangular, striated base attached to the upper third of the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.025, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

3. Rhopalocanium cortinium, n. sp.

Shell slender, ovate, nearly of the same form as, and with similar fenestration to that of Theopera cortina, (Pl. [67], fig. 8). It differs from the latter mainly by the absence of the three thoracic ribs, characteristic of Theopera. Length of the three joints = 1 : 2 : 6, breadth = 1 : 4 : 4. The three wings arise by a broad, triangular, striated base from the upper half of the abdomen, below the lumbar stricture. The cephalic horn and the three divergent wings are shorter, and at the distal end not so much thickened as in Theopera cortina.

Dimensions.—Length of the three joints, a 0.025, b 0.045, c 0.12; breadth, a 0.03, b 0.07, c 0.08.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

4. Rhopalocanium pythia, n. sp.

Rhopalocanium ornatum, Bury, 1862, Polycystins of Barbados, pl. vi. fig. 1.

Shell nearly ovate, with two deep strictures. Length of the three joints = 1 : 4 : 8, breadth = 1 : 4 : 4. Cephalis subspherical, with a conical horn of three times the length. Thorax inflated, abdomen inversely campanulate and prolonged into a short, conical, latticed tube. Pores subregular, circular. Three wings slender, as long as the abdomen, arising by a broader base from the uppermost part of the abdomen, their thickened end being curved inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.15; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

5. Rhopalocanium delphicum, n. sp. (Pl. [67], fig. 9).

Shell nearly spindle-shaped, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis hemispherical, with a slender, conical, curved horn, as long as the hemispherical thorax. Abdomen inversely campanulate, prolonged into a short, conical, latticed tube. Pores subregular, circular. Three wings arising by a narrow base from the uppermost part of the abdomen, slender, cylindrical, S-shaped, curved, divergent, with a thick scaly appendix like a fir-cone at the distal end.

Dimensions.—Length of the three joints, a 0.025, b 0.07, c 0.14; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 599. Rhopalatractus,[[216]] Haeckel, 1881, Prodromus, p. 437.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three lateral wings on the sides of the inversely conical abdomen, which bears a vertical terminal horn on the basal apex.

The genus Rhopalatractus, one of the most remarkable forms of Tricyrtida, differs from the preceding Rhopalocanium, its ancestral form, in the production of a vertical, basal horn, which descends from the basal apex of the inversely conical abdomen, and is opposed to the upper apical horn of the cephalis. The shell becomes here, therefore, exquisitely spindle-shaped.

1. Rhopalatractus pentacanthus, n. sp. (Pl. [68], fig. 11).

Shell very thick-walled, with two sharp strictures. Length of the three joints = 1 : 6 : 8, breadth = 1 : 6 : 7. Cephalis hemispherical, with conical cavity, and a conical horn of twice the length. Thorax subspherical, separated from the abdomen by a deep lumbar stricture, with small, regular, circular, hexagonally-framed pores. Abdomen three-sided prismatic, with three strong, prominent, wing-shaped edges, which are slightly divergent towards the base, and prolonged into three pyramidal feet about as long as the thorax. Pores of the abdomen disposed in longitudinal rows, which are separated by denticulate crests. Abdominal base inversely pyramidal, and prolonged into a very large, cylindrical, basal, axial spine, nearly as long as the whole shell.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.15; breadth, a 0.03, b 0.11, c 0.14.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Rhopalatractus foveolatus, n. sp. (Pl. [68], fig. 10).

Shell slenderly ovate, thick-walled, with rough, dimpled surface. Length of the three joints = 1 : 3 : 5, breadth = 2 : 4 : 4. Cephalis hemispherical, with spherical cavity, and a thick, conical spine of the same length. Thorax subspherical, with subregular, circular pores. Abdomen inversely conical, with larger, irregular, roundish pores, prolonged at the distal end into a cylindrical, axial, basal spine of about half its length. From the middle part of the abdomen arise three lateral, conical feet, which are slightly curved and divergent downwardly, scarcely as long as the basal spine. All five spines are dimpled.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth a 0.04, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Rhopalatractus fusiformis, n. sp.

Shell slender, spindle-shaped, nearly of the same form as in the preceding species. Length of the three joints = 1 : 2 : 6, breadth = 1 : 2 : 2. Cephalis subspherical, with a cylindrical horn three times the length. Pores subregular, circular, of equal breadth in the thorax and in the abdomen, which is prolonged into a cylindrical, axial, basal spine of the same length. From the upper third of the abdomen arise, from a broad triangular base, three conical wings of half the length, divergent and slightly curved inwards.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.15; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

4. Rhopalatractus fenestratus, n. sp. (Pl. [68], fig. 12).

Dictyatractus fenestratus, Haeckel, 1881, Prodromus et Atlas.

Shell nearly spindle-shaped, with two distinct strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 4. Cephalis hemispherical, with a large, club-shaped horn, nearly as long as the abdomen, sulcated by longitudinal ribs, which are elegantly denticulate in the distal half. Thorax subspherical. Abdomen subovate, prolonged into a pyramidal, axial, basal spine, half as long as the thorax. Pores subregular, circular. From the upper half of the abdomen arise three stout, lateral, diverged wings of about the same length, which are curved inwards and fenestrated both at the broad triangular base and at the thickened, three-edged distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 600. Lithochytris,[[217]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with a three-sided pyramidal abdomen, the triangular base of which is prolonged at the three corners into three terminal feet.

The genus Lithochytris differs from all the other Theoperida in the absence of lateral wings and the possession of three divergent, terminal feet, which arise from the three corners of the three-sided pyramidal abdomen. It repeats, therefore, among the Tricyrtida, that characteristic formation which Sethochytris and Tetrahedrina represent among the Dicyrtida. Some species may be derived from Pterocanium, other species from Podocyrtis, by the development of a lattice-plate closing the terminal mouth.

Subgenus 1. Lithochytrodes, Haeckel.

Three feet of the abdomen solid, not fenestrated, representing external apophyses of the triangular shell-base.

1. Lithochytris cortina, n. sp. (Pl. [67], fig. 12).

Shell three-sided pyramidal, without external strictures, but with two internal girdles. Length of the three joints = 2 : 2 : 5, breadth = 3 : 4 : 6. Cephalis large, truncate-pyramidal, with nine deep divergent ribs (and nine longitudinal rows of pores between them), and with a stout pyramidal horn of half the length. The three prominent edges of the thorax and abdomen are prolonged over the base of the pyramid into three very stout, solid, subovate feet, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.1; breadth, a 0.06, b 0.08, a 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Lithochytris pyriformis, n. sp. (Pl. [67], fig. 13).

Shell pyramidal, nearly pear-shaped, with two distinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 3. Cephalis large, pear-shaped, with a short pyramidal horn of half the length. Thorax and abdomen rounded, without prominent edges. Three basal feet pyramidal, solid, nearly vertical, as long as the thorax. Pores irregular, roundish, in the abdomen large, twice to three times as broad as in the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.08; breadth, a 0.04, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

3. Lithochytris tripodium, Ehrenberg.

Lithochytris tripodium, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iv. fig. 11.

Shell pyramidal, nearly pear-shaped, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 5. Cephalis with a horn of the same length, conical. Thorax and abdomen rounded, without prominent edges. Three basal feet conical, solid, strongly divergent, shorter than the thorax. Pores subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.05, c 0.1.

Habitat.—Fossil in Barbados.

Subgenus 2. Lithochytridium, Haeckel.

Definition.—Three feet of the abdomen hollow and fenestrated, representing direct protuberances or corner prolongations of the triangular shell-base.

4. Lithochytris galeata, n. sp. (Pl. [67], fig. 16).

Shell pyramidal, with two sharp strictures. Length of the three joints = 1 : 1 : 4, breadth = 1 : 2 : 4. Cephalis subspherical, with an oblique pyramidal horn of the same length. Thorax somewhat larger. Abdomen inflated, with three sharp, prominent edges, which are prolonged over the shell-base into three pyramidal, hollow, and fenestrated feet, longer than the thorax. Pores subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.025, c 0.1; breadth, a 0.025, b 0.05, c 0.1.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

5. Lithochytris pileata, Ehrenberg.

Lithochytris pileata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. v. fig. 3.

Shell three-sided pyramidal, with deep collar, but indistinct lumbar stricture. Length of the three joints = 2 : 2 : 9, breadth = 3 : 5 : 10. Cephalis with a conical horn of the same length, pear-shaped. Thorax very short and broad. Abdomen inflated, with three sharp, prominent edges, which are prolonged over the shell-base into three pyramidal, hollow and fenestrated feet, the lower edge of which is horizontal. Pores regular, circular, of equal size in the thorax and abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.09; breadth, a 0.03, b 0.05, c 0.1.

Habitat.—Fossil in Barbados.

6. Lithochytris lucerna, n. sp. (Pl. [67], fig. 14).

Shell three-sided pyramidal, with two indistinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 8. Cephalis small, with a horn of the same length, conical. Thorax with subspherical cavity. Abdomen with three rounded, prominent edges, which are prolonged over the shell-base into three conical, hollow, and fenestrated feet, twice as long as the thorax, with a thick, pyramidal, terminal spine. Pores subregular, circular, of equal size in the thorax and abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.04, b 0.06, c 0.16.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

7. Lithochytris lanterna, n. sp. (Pl. [67], fig. 11).

Shell three-sided pyramidal, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis small, with a pyramidal slender horn of twice the length. Thorax with subspherical cavity. Abdomen with three sharp prominent edges, which are prolonged over the convex shell-base into three slender, prismatic, hollow, fenestrated feet, strongly divergent, twice as long as the thorax (seen in fig. 11 from the vaulted base). Pores circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.12.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

8. Lithochytris pyramidalis, Ehrenberg.

Lithochytris pyramidalis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. v. fig. 1.

Shell three-sided pyramidal, without external strictures, but with two internal transverse girdles. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 8. Cephalis with a short horn of half the length, conical. Cavity of the thorax subspherical. Abdomen with three rounded edges, prolonged over the concave base into three pyramidal, hollow, and fenestrated feet, twice as long as the thorax. Pores large, irregular, roundish.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.08, c 0.16.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

9. Lithochytris pteropus, n. sp. (Pl. [67], fig. 15).

Shell three-sided pyramidal, with two indistinct strictures, but with two broad, internal girdles. Length of the three joints = 2 : 2 : 6, breadth = 2 : 3 : 9. Cephalis with a small horn of half the length, pear-shaped. Thorax broader than long. Abdomen with three prominent, rounded edges, prolonged over the concave base into three conical, hollow, and fenestrated feet, twice as long as the thorax. Pores small, circular, irregular, in longitudinal series along the edges.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.12; breadth, a 0.04, b 0.06, c 0.18.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

10. Lithochytris vespertilio, Ehrenberg.

Lithochytris vespertilio, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iv. fig. 10.

Shell three-sided pyramidal, with two indistinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 10. Cephalis with a short horn of half the length, conical. Thorax inflated. Abdomen without prominent edges, divided in the lower half into three large, conical, hollow, and fenestrated feet, twice as long as the thorax. Pores small, irregular, roundish.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.04, b 0.06, c 0.2.

Habitat.—Fossil in Barbados.

Family LXVI. Phormocyrtida, n. fam.

Theophormida et Theophænida, Haeckel, 1881, Prodromus, pp. 436, 437.

Definition.—Tricyrtida multiradiata. (Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, with numerous, four to nine or more, radial apophyses.)

The family Phormocyrtida, composed of the Theophormida and Theophænida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed, and bears numerous radial appendages (usually six or nine, sometimes more, rarely less, four or five). The two subfamilies differ in the shape of the terminal mouth, which is in the Theophormida a simple wide opening, in the Theophænida closed by a lattice-plate. The phylogenetic origin of the Phormocyrtida may be found either in the Podocyrtida or in the Anthocyrtida; they may be derived either from the former by interpolation of interradial, secondary apophyses between the three primary perradial apophyses; or from the latter by development of an abdomen.

The radial apophyses are originally radial ribs, which arise from the base of the cephalis on the collar stricture, run along the thorax and abdomen, and are often prolonged into terminal feet. Whilst in some forms the radial ribs are completely preserved in both joints, they are in other forms only partly visible (in the abdomen), and very often only their free terminal prolongations are preserved in the form of a corona of feet around the mouth of the thorax. This corona is either simple or double. Sometimes also a corona is developed on the lumbar stricture, between the thorax and abdomen.

These apophyses exhibit a remarkable variety in the great subfamily Theophormida, with open mouth. In the small subfamily Theophænida, however, the apophyses appear as six or nine simple lateral wings on the abdomen.

The Theophormida are richly represented not only in the present seas, but also as fossils in Barbados, and numerous remarkable forms have been already described by Ehrenberg, in his genera Calocyclas and Cycladophora. Many Phormocyrtida belong to the most elegant and admirable forms of Radiolaria.

Synopsis of the Genera of Phormocyrtida.

I. Subfamily Theophormida.

Terminal mouth of the abdomen a simple wide opening.

Radial ribs enclosed in the wall of the shell, either the thorax or the abdomen.Radial ribs in the thorax and the abdomen.Abdomen flat, dilated, with a wide open mouth,601. Theophormis.
Abdomen ovate or cylindrical, with constricted mouth,602. Phormocyrtis
Radial ribs in the abdomen only.Peristome with free terminal feet,603. Alacorys.
Peristome smooth, without free feet,604. Cycladophora.
No radial ribs in the shell wall. Peristome with a corona of terminal feet.Terminal corona simple.Abdomen cylindrical or ovate, not dilated,605. Calocyclas.
Abdomen dilated, truncate, conical or discoidal,606. Clathrocyclas.
Corona of feet double.Both coronas terminal,607. Lamprocyclas.
One corona, terminal, the other lumbar,608. Diplocyclas.
II. Subfamily Theophænida.Terminal mouth of the abdomen closed by a lattice-plate.Six lateral wings,609. Hexalatractus.
Nine Lateral wings,610. Theophæna.

I. Subfamily Theophormida.

Terminal mouth of the abdomen a simple wide opening.

Radial ribs enclosed in the wall of the shell, either the thorax or the abdomen.
Radial ribs in the thorax and the abdomen.
Abdomen flat, dilated, with a wide open mouth,
601. Theophormis.
Abdomen ovate or cylindrical, with constricted mouth,
602. Phormocyrtis
Radial ribs in the abdomen only.
Peristome with free terminal feet,
603. Alacorys.
Peristome smooth, without free feet,
604. Cycladophora.
No radial ribs in the shell wall. Peristome with a corona of terminal feet.
Terminal corona simple.
Abdomen cylindrical or ovate, not dilated,
605. Calocyclas.
Abdomen dilated, truncate, conical or discoidal,
606. Clathrocyclas.
Corona of feet double.
Both coronas terminal,
607. Lamprocyclas.
One corona, terminal, the other lumbar,
608. Diplocyclas.
II. Subfamily Theophænida.
Terminal mouth of the abdomen closed by a lattice-plate.
Six lateral wings,
609. Hexalatractus.
Nine Lateral wings,
610. Theophæna.

Subfamily 1. Theophormida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Phormocyrtida with the basal mouth of the shell open (vel Tricyrtida multiradiata aperta).

Genus 601. Theophormis,[[218]] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with numerous radial ribs enclosed in the wall of the thorax and of the flat dilated abdomen; mouth of the latter wide open.

The genus Theophormis commences the series of the Theophormida, or the multiradiate Podocyrtida, as their oldest and simplest form. The three-jointed shell is flat, campanulate or hat-shaped, and pierced by four or more radial ribs, four of which are primary or perradial, the others secondary or interradial. Theophormis may be derived from the similar Sethophormis by development of a lumbar constriction, and a third joint or abdomen.

1. Theophormis callipilium, n. sp. (Pl. [70], figs. 1-3).

Shell flat, hat-shaped, with two sharp annular strictures. Cephalis large, flatly cap-shaped, with small, irregular, square meshes (fig. 3). The collar septum (fig. 2) is composed (as in the following species) of four crossed, thin, horizontal beams, each of which is inserted at the collar stricture by a three forked branch. From the centre of the collar stricture (in the common nodal point of the four beams) there arises a vertical, axial rod, which is inserted at the flat top of the cephalis by five branches (one central and four lateral). Length of the three joints = 1 : 3 : 2, breadth = 2 : 6 : 11. Thorax flat, campanulate, with four primary perradial ribs (prolongations of the four cortinar beams), and numerous (twenty to thirty) interpolated secondary ribs; four of these are in interradial (midway between the four primary ribs), and bisect the four large, semicircular, perradial meshes at the base of the thorax. Network of the thorax and abdomen subregular, with hexagonal meshes and thin bars. Abdomen flatly expanded, somewhat curved, like the brim of a hat, half as broad in the anterior (frontal) part as in the posterior (occipital) part, which is about as broad as the radius of the thorax. The twenty to thirty radial ribs of the abdomen are prolongations of the thoracic ribs, and are somewhat prominent at the margin of the peristome, which appears therefore elegantly indented.

Dimensions.—Length of the three joints, a 0.02 to 0.03, b 0.06 to 0.08, c 0.03 to 0.06; breadth, a 0.05 to 0.08, b 0.2 to 0.3, c 0.4 to 0.5.

Habitat.—Central Pacific, Station 271, surface.

2. Theophormis medusa, n. sp.

Shell flatly campanulate, with two distinct, annular strictures. Length of the three joints = 1 : 2 : 1, breadth = 2 : 5 : 8. Cephalis large, hemispherical. Thorax flatly conical, with four crossed ribs, opposite in pairs in two meridional planes, perpendicular one to another, and prolonged into the flat, nearly discoidal abdomen, which is half as broad as the thorax. The wall of the abdomen is pierced by eight radial ribs; four secondary ribs being interpolated between the four primary. Network of the entire shell very delicate, with regular, hexagonal meshes, and very thin bars. Peristome circular, not dentate.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.04; breadth, a 0.06, b 0.16, c 0.24.

Habitat.—Central Pacific, Station 266, surface.

3. Theophormis cruciata, n. sp.

Shell flat, campanulate, with two distinct annular strictures. Cephalis flat, cap-shaped, with irregular, square meshes. Thorax flat, conical, with hexagonal meshes. Abdomen flatly expanded, of half the breadth, with larger hexagonal meshes. Thorax and abdomen pierced by four stout radial ribs, lying opposite in pairs in two diameters, perpendicular one to another. No secondary or interradial ribs are interpolated between the four primary. Mouth truncate, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.05, b 0.18, c 0.25.

Habitat.—Central Pacific, Station 274, surface.

4. Theophormis senaria, n. sp.

Shell flat, hat-shaped, similar to Theophormis callipilium (Pl. [70], figs. 1-3), but with a different number and arrangement of the piercing radial ribs. The cephalis and its collar septum exhibit the same formation as in Sethophormis hexalactis, described above (p. [1245], Pl. [56], fig. 6.) The caudal and sternal ribs, which are opposed in the sagittal plane, are simple, whilst the two lateral ribs are forked. In the flat abdomen there are six secondary or interradial ribs, interpolated between the six primary or perradial ribs of the thorax. Delicate network with regular, hexagonal meshes.

Dimensions.—Length of the three joints, a 0.035, b 0.075, c 0.025; breadth, a 0.07, b 0.2, c 0.3.

Habitat.—Central Pacific, Station 272, surface.

Genus 602. Phormocyrtis,[[219]] n. gen.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with numerous radial ribs enclosed in the wall of the thorax, and of the ovate or cylindrical abdomen; mouth of the latter constricted.

The genus Phormocyrtis differs from the preceding Theophormis in the ovate or cylindrical form of the abdomen, the mouth of which is more or less constricted. The former exhibits, therefore, the same relation to the latter that Sethamphora bears to Sethophormis among the Dicyrtida. Phormocyrtis may be derived directly either from Sethamphora by development of an abdomen, or from Pterocorys or Theopilium by multiplication of the three radial ribs.

1. Phormocyrtis carinata, n. sp.

Shell ovate, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout pyramidal horn of twice the length, and few very small pores. Pores in the campanulate thorax and the inflated abdomen regular, circular, small, and numerous. Six stout prominent ribs, beginning from the collar stricture, arise along the thorax and abdomen, and reach the constricted mouth, which is half as broad as the abdomen. (This species is very similar to Pterocorys carinata, from which it differs in the six complete radial ribs of the shell-wall.)

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Phormocyrtis fastosa, Haeckel.

Eucyrtidium fastosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 19.

Shell ovate, with two distinct strictures. Length of the three joints = 1 : 3 : 3, breadth = 1 : 5 : 6. Cephalis ovate, with a stout pyramidal horn of the same length, and numerous rather large pores. Pores in the campanulate thorax and the inflated abdomen much smaller, very numerous, regular, hexagonal. Along these two joints arise nine delicate, divergent ribs; these extend almost to the wide mouth, which is slightly constricted.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.08; breadth, a 0.02, b 0.1, c 0.12.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.

3. Phormocyrtis costata, n. sp. (Pl. [69], fig. 6).

Shell smooth, with sharp collar, but indistinct lumbar stricture. Length of the three joints = 2 : 5 : 5, breadth = 2 : 6 : 6. Cephalis conical, with a stout pyramidal horn of twice the length. Thorax and abdomen together nearly cylindrical, constricted towards both poles, with thirty to forty longitudinal ribs, which are nearly parallel, vertical in the middle part, and convergent towards both poles; alternate with the same number of longitudinal rows of regular, circular pores. Mouth with a broad, hyaline, only slightly constricted peristome.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.1; breadth, a 0.04, b 0.12, c 0.12.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Phormocyrtis embolum, Haeckel.

Eucyrtidium embolum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 5.

Shell smooth, with sharp collar, but indistinct lumbar stricture. Length of the three joints = 3 : 7 : 10, breadth = 3 : 9 : 7. Cephalis subspherical, with a pyramidal horn of the same length. Thorax campanulate; abdomen inversely truncate, conical; both with sixteen to twenty longitudinal ribs, and alternate longitudinal rows of small circular pores, converging towards the two poles. Mouth truncate, with broad hyaline peristome.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.1; breadth, a 0.03, b 0.09, c 0.07.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

5. Phormocyrtis quadrata, n. sp.

Shell ovate, papillate, with two slight strictures. Length of the three joints = 2 : 3 : 13, breadth = 4 : 6 : 11. Cephalis hemispherical, small, with two divergent, pyramidal horns of twice the length. Along the hemispherical thorax and the ovate inflated abdomen run twenty-four to thirty curved ribs, converging towards the two poles, and alternate with the same number of longitudinal rows of circular, regular pores, disposed in ten to twelve transverse rows. Each pore with a square, elevated frame. Mouth constricted, only one-third as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.13; breadth, a 0.04, b 0.06, c 0.11.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

6. Phormocyrtis longicornis, n. sp. (Pl. [69], fig. 15).

Theocorys longicornis, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell slender, ovate, rough, with two slight strictures. Length of the three joints = 3 : 8 : 12, breadth = 4 : 10 : 11. Cephalis hemispherical, with a very large, cylindrical horn, about as long as the shell. Thorax hemispherical, with regular, circular, hexagonally-framed pores. Abdomen subcylindrical, with twenty to twenty-four nearly parallel undulate ribs, and alternate longitudinal rows of regular, circular pores. Mouth constricted, circular, about half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.12; breadth, a 0.04, b 0.1, c 0.11.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

Genus 603. Alacorys,[[220]] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with numerous radial ribs in the abdomen, which are prolonged over the mouth into free feet.

The genus Alacorys and the following Cycladophora differ from the preceding two genera in the formation of the radial ribs, which arise from the lumbar stricture, and lie in the wall of the abdomen, but are absent on the thorax. The shell is usually large, more or less pyramidal or conical, with a wide open terminal mouth. The latter is in Cycladophora simply truncate, whilst in Alacorys it is surrounded by from four to twelve or more terminal feet, prolongations of the abdominal ribs. According to the different number of these (four, five, six, or more) some subgenera may be distinguished, as Tetralacorys, Pentalacorys, Hexalacorys, &c.

Subgenus 1. Tetralacorys, Haeckel, 1881, Prodromus, p. 436.

Definition.—Peristome armed with four feet, opposite in two meridian planes, which are perpendicular to one another.

1. Alacorys lutheri, n. sp. (Pl. [65], fig. 4).

Shell papillate, with distinct collar stricture. Length of the three joints = 3 : 6 : 6, breadth = 3 : 8 : 10. Cephalis subspherical, with a pyramidal horn of the same length. Thorax tuberculate, nearly hemispherical, with circular pores of very different sizes. From the margin of its wide open mouth descend four stout perradial ribs, which are forked at the distal end, and by communication of their fork-branches form the four large, pentagonal holes of the abdomen. From the middle of the lower margin of the holes descend four parallel, vertical, slender feet, about as long as the shell. This species is dedicated to the memory of the great Reformer, Martin Luther.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.06; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Alacorys tetracantha, Haeckel.

Podocyrtis tetracantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 2.

? Podocyrtis parvipes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 5.

Shell rough, with distinct collar stricture. Length of the three joints = 1 : 3 : 5, breadth = 1 : 4 : 6. Cephalis subspherical, with a rudimentary conical horn. Thorax campanulate, with irregular, roundish pores of different sizes. Abdomen inflated, with a small number of very large irregular holes, intermingled with smaller roundish holes. From the margin of the wide open mouth descend, nearly vertically, four strong vertical feet, which are about as long as the shell, and slightly curved, with convex outlines. Podocyrtis parvipes of Ehrenberg seems to be only a mutilated specimen of this species.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.09; breadth, a 0.03, b 0.08, c 0.13.

Habitat.—Fossil in Barbados.

Subgenus 2. Pentalacorys, Haeckel, 1881, Prodromus, p. 436.

Definition.—Peristome armed with five feet, one of which is odd and occipital, the other four paired and lateral.

3. Alacorys pentacantha, Haeckel.

Podocyrtis pentacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 1.

Shell rough, with slight collar stricture. Length of the three joints = 1 : 2 : 3, breadth = 1 : 4 : 6. Cephalis subspherical, with a rudimentary conical horn. Thorax campanulate, with subregular, circular, quincuncial pores. Abdomen wider, campanulate, with a small number of very large and irregular, roundish holes. From the peristome descend five stout conical feet, which are slightly curved and divergent, nearly as long as the shell.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.025, b 0.08, c 0.11.

Habitat.—Fossil in Barbados.

4. Alacorys bismarckii, n. sp. (Pl. [65], fig. 3).

Shell spiny, with distinct collar stricture. Length of the three joints = 1 : 4 : 5, breadth = 2 : 7 : 10. Cephalis hemispherical, with a very stout, dimpled, conical horn of the same length. Thorax campanulate, spiny, with regular, circular pores. Abdomen wider, campanulate, with larger conical spines, and a small number of irregular, roundish, very large holes. From the peristome descend, nearly vertically, five very large cylindrical feet, nearly twice as long as the shell; they are S-shaped, curved, spinulate in the distal half, and armed at the proximal base with two stout conical spines, the smaller of which is directed inwards, the larger curved upwards. Dedicated to Prince Otto von Bismarck, the Reconstructor of the German Empire.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.04, b 0.14, c 0.2.

Habitat.—Western Tropical Pacific (north of New Guinea), Station 220, depth 1100 fathoms.

Subgenus 3. Hexalacorys, Haeckel, 1881, Prodromus, p. 436.

Definition.—Peristome armed with six feet, three of which are primary or perradial (Podocyrtis), the three other alternate, secondary or interradial.

5. Alacorys friderici, n. sp. (Pl. [65], fig. 1).

Shell conical, rough, with sharp collar stricture. Cephalis subspherical, with a large, oblique, prismatic horn, twice the length. Thorax campanulate, with regular, circular pores (six to eight in its length). Abdomen wider, campanulate, with a small number of very large pores (three to four in the course of its length). Peristome with six very large divergent feet, which are about as long as the shell, cylindrical, irregularly curved. The specimen figured was observed living, with expanded pseudopodia. The central capsule exhibited four large pear-shaped lobes, filling up the shell-cavity; each contained an oil-globule in the thoracic part. The undivided cephalic part of the capsule enclosed a nucleus, from which four lobes protruded through the four collar pores into the thorax. Dedicated to Frederick the Great, the Royal Philosopher of Potsdam.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.04, b 0.09, c 0.14.

Habitat.—North Atlantic, Canary Islands, Lanzerote (Haeckel), surface.

6. Alacorys guilelmi, n. sp. (Pl. [65], fig. 2).

Shell thorny, with distinct collar stricture. Length of the three joints = 1 : 3 : 4, breadth = 2 : 5 : 8. Cephalis hemispherical, with a rudimentary conical horn. Thorax hemispherical, spiny, with regular, circular pores. Abdomen wider, campanulate, papillate, with a small number of very large circular holes. Peristome with six diverging feet, which are about as long as the shell, at the base conical, thickened, and at the distal end curved inwards, with a spinulate knob. Dedicated to the German Emperor, Wilhelm.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.03, b 0.1, c 0.16.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

7. Alacorys hexacantha, n. sp.

Shell thorny, with slight collar stricture. Length of the three joints = 2 : 5 : 7, breadth = 4 : 10 : 14. Cephalis flat, cap-shaped, with a rudimentary conical horn. Thorax campanulate, with regular, circular pores. Abdomen wider, campanulate, with a small number of very large polygonal pores. Peristome with six large divergent feet, which are longer than the shell, cylindrical, and slightly curved, in the proximal half convex, in the distal half concave.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.04, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

8. Alacorys hexapleura, n. sp.

Shell spiny, with distinct collar stricture. Length of the three joints = 2 : 10 : 8, breadth = 3 : 11 : 10. Cephalis hemispherical, large, hyaline, and thick-walled, with a very stout, conical horn of the same length. Thorax pear-shaped, with numerous, regular, circular pores and conical spines, the size of which increases gradually towards the deep, lumbar stricture. Abdomen truncate, conical, with irregular, roundish pores, and six very strong, straight, divergent ribs, prolonged into six short, conical feet.

Dimensions.—Length of the three joints, a 0.04, b 0.2, c 0.16; breadth, a 0.06, b 0.22, c 0.2.

Habitat.—Fossil in Barbados.

Subgenus 4. Octalacorys, Haeckel.

Definition.—Peristome armed with eight feet, four of which are primary or perradial (corresponding to those of Tetralacorys), the other four alternate, secondary, or interradial.

9. Alacorys aculeata, Haeckel.

Podocyrtis aculeata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xiii. fig. 3.

Podocyrtis aculeata, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 34.

Shell spiny, with deep collar stricture. Length of the three joints = 2 : 5 : 8, breadth = 2 : 7 : 10. Cephalis subspherical, with a slender, conical horn of twice the length. Thorax campanulate, thorny, with regular, circular pores. Abdomen wider, campanulate, with a small number of very large, regular, hexagonal meshes, and stout spines in the nodal points. Peristome with eight strong conical feet, which are nearly parallel, little curved (convex at the outside), and sometimes all of the same size (equal to the length of the shell); at other times different, four larger alternating with four smaller feet.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.08; breadth, a 0.025, b 0.07, c 0.1.

Habitat.—Fossil in Barbados.

10. Alacorys octacantha, n. sp.

Shell spiny, with deep collar stricture. Length of the three joints = 2 : 8 : 6, breadth = 3 : 7 : 7. Cephalis ovate, with a short, conical horn. Thorax pear-shaped, spiny, with regular, circular pores, similar to Cycladophora erinaceus, Ehrenberg (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 2). Abdomen truncate, conical, with irregular, roundish pores, and eight stout, straight, thorny, divergent ribs of equal size, which are prolonged into eight free, conical, spiny feet of the same length.

Dimensions.—Length of the three joints, a 0.04, b 0.16. c 0.12; breadth, a 0.06, b 0.14, c 0.14.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 5. Ennealacorys, Haeckel.

Definition.—Peristome armed with nine feet, three of which are primary or perradial, the other six secondary or interradial.

11. Alacorys enneacantha, n. sp.

Shell papillate, with slight collar stricture. Length of the three joints = 2 : 4 : 8, breadth = 3 : 6 : 9. Cephalis hemispherical, with a stout, conical horn of twice the length. Thorax campanulate, with subregular, circular pores, and small, conical papillæ. Thorax wider, campanulate, with circular pores, and conical papillæ of three times the size. Peristome with nine widely divergent, little curved, conical feet, about as long as the shell. Similar to Podocyrtis ventricosa, Ehrenberg (1875, loc. cit., Taf. xvi. fig. 3), different mainly in the feet.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

12. Alacorys gigas, n. sp.

Shell thorny, with distinct collar stricture. Length of the three joints = 1 : 4 : 2, breadth = 1 : 5 : 4. Cephalis ovate, with a short, conical horn of about half the length. Thorax campanulate, thorny, with small, regular, circular pores, very similar to Cycladophora gigas, Ehrenberg (loc. cit., 1875, p. 68, Taf. xviii. fig. 1). Abdomen truncate, conical, smooth, with irregular, roundish pores, and nine stout and straight, little divergent ribs, which are prolonged into nine cylindrical, pointed feet of the same length.

Dimensions.—Length of the three joints, a 0.05, b 0.2, c 0.1; breadth, a 0.05, b 0.25, c 0.2.

Habitat.—Fossil in Barbados.

Subgenus 6. Polyalacorys, Haeckel.

Definition.—Peristome with numerous (ten to twenty or more) prominent feet, three or four of which are primary and perradial, the others secondary and interradial.

13. Alacorys dodecantha, n. sp.

? Podocyrtis schomburgkii, var., Bury, 1862, Polycystins of Barbados, Taf. xii. fig. 3.

Shell smooth, with slight collar stricture. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 7. Cephalis ovate, with a conical horn of the same length. Thorax campanulate, with regular, circular pores. From its margin arise twelve stout, little curved, radial beams, which are widely divergent, and connected in the middle part by a transverse circular ring, so that the abdomen exhibits twelve large triangular holes, and at the peristome, alternating with these, twelve free conical feet of the same length.

Dimensions.—Length of the three joints, a 0.04, b 0.09, c 0.11; breadth, a 0.03, b 0.12, c 0.22.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms; also fossil in Barbados.

14. Alacorys carcinus, n. sp. (Pl. [74], fig. 9).

Calocyclas carcinus, Haeckel, 1879, Atlas, loc. cit.

Podocyrtis schomburgkii, var., Bury, 1862, Polycystins of Barbados, pl. i. fig. 2; pl. xii. fig. 4.

Shell rough, with distinct collar stricture. Length of the three joints = 1 : 4 : 4, breadth = 2 : 6 : 6. Cephalis hemispherical, with a large, cylindrical, bent spine of three times the length. Thorax inflated, campanulate, with large, regular, circular pores. Abdomen truncate, conical, with three to four transverse rows of regular, square pores, produced by eighteen divergent, straight ribs, which are connected by three to four horizontal rings. Distal end of the ribs prolonged into eighteen slender, conical feet, which are about as long as the thorax and slightly curved inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.05, b 0.12, c 0.12.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

15. Alacorys polyacantha, n. sp.

Shell spiny, with deep collar stricture. Length of the three joints = 3 : 9 : 10, breadth = 4 : 12 : 16. Cephalis hemispherical, with a stout conical horn of the same length. Thorax campanulate, with regular, circular pores and conical spines, increasing in size towards the deep lumbar stricture. Abdomen truncate, conical, with twenty to thirty divergent, straight ribs, which are connected by four to six transverse rings, and prolonged into free conical feet of half the length. Therefore four to six transverse rings of regular, square pores occur.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.1; breadth, a 0.04, b 0.12, c 0.16.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

16. Alacorys ornata, Haeckel.

Cryptoprora ornata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. fig. 8.

Shell ovate, smooth, without external strictures, but with two internal annular septa. Length of the three joints = 3 : 5 : 4, breadth = 3 : 6 : 5. Cephalis subspherical, partly enclosed by the uppermost part of the thorax, without horn, or with a small rudimentary horn. Pores subregular, circular, half as broad in the cephalis as in the two other joints. Thorax campanulate. Abdomen truncate, with eighteen to twenty-four parallel, vertical, longitudinal ribs, which are prolonged into slender, free, conical feet of the same length. (This remarkable species may be derived from Carpocanium by apposition of a third joint.)

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.04; breadth, a 0.03, b 0.06, c 0.05.

Habitat.—Fossil in Barbados.

Genus 604. Cycladophora,[[221]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with four to six or more radial ribs in the abdomen, the terminal mouth of which is truncate, without feet.

The genus Cycladophora differs from the preceding Alacorys, its probable ancestral genus, in the absence of free terminal feet, the radial ribs of the abdomen being connected by transverse beams throughout their whole length. The number of the regularly disposed ribs (four to six or more) may also here be used for the distinction of different subgenera.

Subgenus 1. Lampterium, Haeckel, 1881, Prodromus, p. 434.

Definition.—Abdomen with four radial ribs, opposite in pairs in two meridian planes, perpendicular one to another.

1. Cycladophora gœtheana, n. sp. (Pl. [65], fig. 5).

Shell shaped like a lantern, with two sharp strictures. Length of the three joints = 1 : 2 : 12, breadth = 1 : 4 : 7. Cephalis hemispherical, with a slender pyramidal horn of three times the length. Thorax twice as large, thorny, hemispherical, with regular, circular pores. Abdomen very long, nearly four-sided prismatic, with four superior smaller, and four inferior larger holes; the former separated by four short, divergent, perradial, the latter by four long, parallel, vertical, interradial bars. Mouth square, four-lobed. Dedicated to Wolfgang Goethe.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.24; breadth, a 0.03, b 0.07, c 0.1 to 0.14.

Habitat.—Central Pacific, Stations 265 to 269, depth 2550 to 2900 fathoms.

2. Cycladophora tetrapleura, n. sp.

Shell very similar to the preceding species, but differing in the following characters: Cephalis conical, with a horn of the same length. Thorax campanulate. Four ribs of the abdomen not parallel and vertical, but more or less divergent. Length of the three joints = 1 : 2 : 8, breadth = 1 : 2 : 4. Whole shell slender, pyramidal. Mouth square, four-lobed.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.24; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

3. Cycladophora lanterna, n. sp.

Shell very similar to the two preceding species, but differing in the following characters. Cephalis subspherical, with a thick, pyramidal horn of the same breadth, and three times the length. Thorax hemispherical, with circular, hexagonally-framed pores. Abdomen ovate, with four convex ribs, and twelve large holes, four superior smaller pentagonal, four intermediate very large, ovate, and four inferior, small, triangular holes. Mouth little constricted, nearly circular.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.22; breadth, a 0.025, b 0.08, c 0.11.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Subgenus 2. Lamptidium, Haeckel.

Definition.—Abdomen with six radial ribs (three primary or perradial, and three alternate, secondary or interradial).

4. Cycladophora hexapleura, n. sp.

Lanterna chinensis, Bury, 1862, Polycystins of Barbados, pl. xiii. fig. 7.

Shell shaped like a lantern, with six sides and two sharp strictures. Length of the three joints = 1 : 2 : 8, breadth = 1 : 2 : 4. Cephalis hemispherical, with a conical spine of the same length. Thorax twice as large, hemispherical, with regular, circular pores. Abdomen nearly six-sided prismatic, with six descending, little curved ribs, and eighteen large holes between them; six superior holes interradial, ovate, six intermediate holes very large, perradial, ovate, six inferior holes triangular, interradial. Mouth six-lobed.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.16; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

5. Cycladophora pyramidalis, n. sp.

Podocyrtis sp., Bury, 1862, Polycystins of Barbados, pl. xii. fig. 2.

Shell slender, pyramidal, with six sides and two slight strictures. Length of the three joints = 1 : 4 : 12, breadth = 1 : 4 : 8. Cephalis subspherical, with a conical horn of twice the length. Thorax conical, with regular, circular pores. Abdomen truncate, pyramidal, with six strong, divergent, straight ribs, which are connected by five to six transverse, hexagonal rings; therefore six longitudinal rows of large, roundish, quadrangular meshes (four to five meshes in each row). Mouth hexagonal.

Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.3; breadth, a 0.03, b 0.1, c 0.2.

Habitat.—Fossil in Barbados.

6. Cycladophora spinosa, n. sp.

Shell spiny, with two deep strictures. Length of the three joints = 1 : 4 : 3, breadth = 1 : 5 : 4. Cephalis subspherical, with a stout conical horn of the same length. Thorax ovate, with regular, circular pores, and numerous conical spines. Abdomen truncate, conical, with irregular, roundish pores, and six strong, divergent ribs. Mouth circular.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.09; breadth, a 0.03, b 0.15, c 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.

Subgenus 3. Lamptonium, Haeckel.

Definition.—Abdomen with nine radial ribs (three primary or perradial, and six secondary or interradial).

7. Cycladophora enneapleura, n. sp.

Shell spiny, with two sharp strictures. Length of the three joints = 1 : 5 : 3, breadth = 2 : 7 : 4. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with regular, circular pores, and conical thorax. Abdomen cylindrical, with nine straight, parallel ribs, and irregular, roundish pores. Mouth circular. (Similar to Cycladophora gigas, Ehrenberg, 1875, loc. cit., Taf. xviii. fig. 1, but differing in the possession of nine abdominal ribs.)

Dimensions.—Length of the three joints, a 0.03, b 0.15, c 0.1; breadth, a 0.06, b 0.2, c 0.12.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

8. Cycladophora nonagona, n. sp.

Shell spiny, with two distinct strictures. Length of the three joints = 3 : 10 : 7, breadth = 2 : 9 : 8. Cephalis pear-shaped, with a stout pyramidal horn of the same length. Thorax pear-shaped, with regular, circular pores, and conical horns, increasing in size towards the base. Abdomen truncate, pyramidal, with nine straight, spinulate ribs, and nine even faces between them, with irregular, roundish pores. Mouth nonagonal.

Dimensions.—Length of the three joints, a 0.06, b 0.2, c 0.14; breadth, a 0.05, b 0.18, c 0.16.

Habitat.—Fossil in Barbados.

Subgenus 4. Cyclampterium, Haeckel.

Definition.—Abdomen truncate, conical or campanulate, with numerous (ten to twenty or more) divergent ribs. Mouth wide open, truncate.

9. Cycladophora pantheon, n. sp. (Pl. [68], fig. 3).

Shell dome-shaped, with slight collar and deep lumbar stricture. Length of the three joints = 1 : 6 : 5, breadth = 1 : 7 : 8. Cephalis small, with a conical horn of the same length. Thorax cupola-shaped, with large, regular, circular pores, and numerous pyramidal tubercles. Abdomen with twelve (sometimes eleven or thirteen) slender, divergent ribs, which are connected at equal distances by four to six horizontal rings, and so produce twelve longitudinal rows of large, regular, square meshes.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.1; breadth, a 0.03, b 0.14, c 0.15.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

10. Cycladophora dodecapleura, n. sp.

Shell cupola-shaped, with two deep strictures. Length of the three joints = 2 : 5 : 6, breadth = 2 : 7 : 10. Cephalis hemispherical, with a conical horn of twice the length. Thorax subspherical, truncate at both poles, thorny, with regular, circular pores. Abdomen in the upper half with a coronal of twelve large ovate holes, separated by twelve divergent, slender ribs, in the lower half with curved, convergent prolongations of the twelve ribs, and numerous small, irregular, roundish pores.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.06; breadth, a 0.02, b 0.07, c 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

11. Cycladophora campanula, n. sp.

Shell campanulate, with two slight strictures. Length of the three joints = 2 : 4 : 5, breadth = 2 : 6 : 10. Cephalis ovate, with a conical horn of the same length. Thorax campanulate, rough, with regular, circular pores. Abdomen dilated, with fifteen to twenty slender, divergent, little curved ribs, which are connected by two or three horizontal rings, and from two or three transverse rows of large, roundish, square pores.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.12, c 0.2.

Habitat.—North Atlantic, Bermuda, surface; also fossil in Barbados.

12. Cycladophora spatiosa, Ehrenberg.

Cycladophora spatiosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. figs. 5, 6.

Shell campanulate, with two slight strictures. Length of the three joints = 2 : 6 : 9, breadth = 3 : 8 : 14. Cephalis subspherical, with a conical horn of the same length. Thorax campanulate, smooth, with regular, circular pores. Abdomen truncate, conical, with sixteen to twenty-four divergent ribs, which are straight or slightly curved, and connected by from four to six transverse, circular rings. The large regular meshes, so produced, form sixteen to twenty-four longitudinal series, and are rounded in the upper, square in the lower transverse rows.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.09; breadth, a 0.03, b 0.08, c 0.14.

Habitat.—Fossil in Barbados.

13. Cycladophora favosa, n. sp. (Pl. [62], figs. 5, 6).

Shell dome-shaped, without collar stricture, but with a deep lumbar stricture. Cephalis flat, cap-shaped, without horn, or with a rudimentary conical horn, with small circular pores. Length of the three joints = 1 : 4 : 3, breadth = 2 : 5 : 4. Thorax subspherical, rough, with regular, circular, hexagonally-framed pores. Abdomen truncate, conical, with eighteen to twenty-four prominent ribs; between every two ribs only two or three ovate pores occur. Mouth circular, with eighteen to twenty-four teeth. The shape of the abdomen is rather variable (figs. 5, 6).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.04, b 0.09, c 0.07.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 5. Cyclamptidium, Haeckel.

Definition.—Abdomen nearly cylindrical or prismatic, with numerous (ten to twenty or more) straight, vertical, parallel ribs. Mouth wide open, truncate.

14. Cycladophora fenestrata, n. sp. (Pl. [68], fig. 2).

Shell rough, with two slight strictures. Length of the three joints = 1 : 5 : 5, breadth = 1 : 6 : 5. Cephalis conical, with a conical, dimpled horn of twice the length. Thorax nearly spherical, with regular, circular pores, and small conical spines. Abdomen cylindrical, with eighteen stout, parallel, vertical ribs, which are connected by six to eight horizontal, circular rings; therefore regular transverse and longitudinal rows of square or circular pores occur. Mouth truncate, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.1; breadth, a 0.03, b 0.12, c 0.1.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

15. Cycladophora stiligera, Ehrenberg.

Cycladophora stiligera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 3.

Shell smooth, with two distinct strictures. Length of the three joints = 2 : 7 : 8, breadth = 2 : 9 : 7. Cephalis subspherical, with a conical horn of twice the length. Thorax subspherical, smooth, with regular, circular pores. Abdomen cylindrical, with twelve parallel, vertical ribs, which are connected by three to four broad, horizontal rings; therefore subregular, transverse, and longitudinal rows of roundish pores are present. Mouth truncate, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.08; breadth, a 0.02, b 0.09, c 0.07.

Habitat.—Fossil in Barbados.

Genus 605. Calocyclas,[[222]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a simple corona of terminal feet around the truncate mouth. Abdomen not dilated, cylindrical or ovate. No ribs in the shell-wall.

The genus Calocyclas, and the three following closely allied genera, differ from the four preceding genera of Theophormida in the absence of radial or longitudinal ribs in the wall of the thorax and abdomen. These are completely reduced, and their terminal prolongations only remain, forming a simple or double corona around the mouth of the abdomen. They correspond therefore to Carpocanium and Anthocyrtis among the Dicyrtida. In Calocyclas the corona is simple. The mouth is not dilated, but often constricted, and the abdomen is cylindrical or ovate, not conical. The teeth of the corona are usually vertical or convergent.

Subgenus 1. Calocycletta, Haeckel.

Definition.—Thorax and abdomen smooth, without spines or thorns.

1. Calocyclas veneris, n. sp. (Pl. [74], fig. 5).

Shell smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 3. Cephalis ovate, with a large, triangular, prismatic horn of three times the length. Thorax hemispherical; abdomen cylindrical; both with regular, circular pores of equal size. Mouth truncate, with a corona of nine to twelve vertical, lamellar feet, which are as long as the abdomen, rectangular, twice as broad as their distance apart, and truncate at the end.

Dimensions.—Length of the three joints, a 0.03 to 0.04, b 0.06 to 0.08, c 0.04 to 0.06; breadth, a 0.03 to 0.04, b 0.09 to 0.11, c 0.08 to 0.1.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, many stations; surface, and in various depths.

2. Calocyclas virginis, n. sp. (Pl. [74], fig. 4).

Shell smooth, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 1 : 2 : 1, breadth = 1 : 4 : 3. Cephalis ovate, with a slender, conical horn, little shorter than the shell. Thorax subspherical. Abdomen nearly cylindrical, little contracted towards the peristome. Pores regular, circular, twice as broad in the thorax as in the abdomen, where they are separated by slight longitudinal ribs. Corona of the peristome composed of sixteen to twenty-four vertical, lamellar feet, which are longer than the abdomen, rectangular, and truncate at the end.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.05; breadth, a 0.03, b 0.11, c 0.09.

Habitat.—Central Pacific, Station 225, depth 4475 fathoms.

3. Calocyclas minervæ, n. sp.

Shell smooth, with two deep strictures, similar to Cycladophora stiligera. Length of the three joints = 1 : 4 : 3, breadth = 1 : 4 : 3. Cephalis subspherical, with a large, conical horn of three times the length. Thorax subspherical, with small, regular, circular pores. Abdomen cylindrical, with truncate mouth and few irregular pores of different sizes, commonly arranged in three or four subregular, transverse rows, with large intervening distances. Peristome with a corona of twelve to twenty vertical, lamellar feet, which are about as long as the abdomen, and truncate at the end (in Ehrenberg's figure these are broken off).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.02, b 0.09, c 0.07.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

4. Calocyclas amicæ, n. sp. (Pl. [74], fig. 2).

Shell smooth, with two slight strictures. Length of the three joints = 2 : 4 : 5, breadth = 2 : 5 : 5. Cephalis subspherical, with a pyramidal horn of the same length. Thorax campanulate-conical; abdomen nearly cylindrical; both with small, subregular, circular pores. Peristome with a corona of twelve to fifteen small, triangular feet, only as large as the thickness of the shell-wall, and separated by distances of twice the size.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

5. Calocyclas sacerdotis, n. sp.

Shell smooth, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a pyramidal horn of three times the length. Thorax campanulate, conical; abdomen twice the length, cylindrical; both with small, regular, circular pores. Peristome somewhat constricted, with a corona of nine to twelve conical feet, which are as long as the cephalis, and with the ends curved inwards, protecting the mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.12; breadth, a 0.03, b 0.09, c 0.09.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

6. Calocyclas vestalis, n. sp. (Pl. [74], fig. 3).

Shell smooth, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 3. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate; abdomen nearly cylindrical; both with regular, hexagonal pores, three times as broad as the bars. Peristome constricted, half as broad as the abdomen, with a corona of nine conical, vertical feet as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.1; breadth, a 0.035, b 0.1, c 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 2. Calocyclissa, Haeckel.

Definition.—Thorax spiny or thorny; abdomen smooth.

7. Calocyclas turris, Ehrenberg.

Calocyclas turris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xviii. fig. 7.

Shell with two sharp strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 5 : 4. Cephalis hemispherical, with a stout conical horn of the same length. Thorax subspherical, thorny with small, regular, circular, quincuncial pores. Abdomen cylindrical, smooth, nearly hyaline, with very scarce, irregular, widely scattered pores. Peristome with a corona of fifteen to twenty broad, lamellar, vertical, truncate feet, about as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.03, b 0.1, c 0.08.

Habitat.—Fossil in Barbados.

8. Calocyclas hyalogaster, n. sp.

Shell with two sharp strictures. Length of the three joints = 1 : 4 : 6, breadth = 1 : 4 : 3. Cephalis subspherical, with a conical horn of twice the length. Thorax subspherical, thorny, with regular, circular pores. Abdomen cylindrical, smooth, quite hyaline, without any pores. Peristome with a corona of twelve broad, lamellar, vertical, truncate feet, half as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.12; breadth, a 0.02, b 0.08, c 0.06.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

9. Calocyclas erinaceus, Haeckel.

Cycladophora erinaceus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 2.

Shell with two sharp strictures. Length of the three joints = 2 : 9 : 5, breadth = 3 : 9 : 5. Cephalis subspherical, rough, with a short and broad conical horn of half the length. Thorax ovate, densely covered with conical spines as long as the horn, and with regular, circular, quincuncial pores. Abdomen cylindrical, smooth, with irregular roundish pores of different sizes. Peristome with twelve to fifteen vertical, broad, lamellar, truncate feet half as long as the abdomen (in Ehrenberg's figure these are broken off).

Dimensions.—Length of the three joints, a 0.04, b 0.18, c 0.1; breadth, a 0.06, b 0.18, c 0.1.

Habitat.—Fossil in Barbados.

10. Calocyclas gigas, Haeckel.

Cycladophora gigas, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 1.

Shell with two sharp strictures. Length of the three joints = 2 : 5 : 3, breadth = 2 : 6 : 4. Cephalis subspherical, rough, with a short and broad conical horn of half the length. Thorax subspherical, campanulate, thorny, with subregular, circular pores (smaller and more numerous than in the preceding). Abdomen cylindrical, smooth, with a small number of sparsely disposed, roundish, irregularly scattered pores. Peristome with twenty to thirty short, lamellar, truncate, vertical feet about half as long as the cephalis.

Dimensions.—Length of the three joints, a 0.06, b 0.15, c 0.09; breadth, a 0.06, b 0.18, c 0.12.

Habitat.—Fossil in Barbados.

Subgenus 3. Calocycloma, Haeckel.

Definition.—Thorax smooth; abdomen spiny or thorny.

11. Calocyclas casta, n. sp. (Pl. [73], fig. 10).

Shell ovate, with two sharp strictures. Length of the three joints = 1 : 2 : 8, breadth = 2 : 4 : 8. Cephalis hemispherical, with a strong pyramidal horn of twice the length. Thorax campanulate, smooth, with small, regular, circular pores. Abdomen inflated, subspherical, covered with large conical spines, and large intervening circular pores (four times as broad as the thoracic pores). Mouth constricted, only one-third as broad as the abdomen, with a peristome of nine to twelve conical vertical feet as long as the abdominal spines. (In the specimen figured they were broken off.)

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.15; breadth, a 0.04, b 0.08, c 0.15.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

12. Calocyclas pudica, n. sp.

Shell ovate, with two distinct strictures. Length of the three joints = 1 : 3 : 8, breadth = 1 : 4 : 6. Cephalis subspherical, with a conical horn of three times the length. Thorax and abdomen nearly of the same shape as in the preceding species, but more slender and the regular, circular pores of the abdomen only twice as broad as the thoracic pores. Conical spines of the abdomen only half as large, but more numerous. Peristome constricted, half as broad as the abdomen, with sixteen to twenty short, conical, vertical feet as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.16; breadth, a 0.025, b 0.08, c 0.12.

Habitat.—Central Pacific Station 266, depth 2750 fathoms.

Subgenus 4. Calocyclura, Haeckel.

Definition.—Thorax and abdomen spiny or thorny.

13. Calocyclas parthenia, n. sp. (Pl. [74], fig. 1).

Shell nearly ovate, with thorny surface, and two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 5. Cephalis hemispherical, armed with numerous short, conical thorns, and with a pyramidal, very large, vertical horn as long as the thorax, and on the basal half as broad as the cephalis. Thorax hemispherical, separated by a slight stricture from the broader, barrel-shaped abdomen, which is a little constricted at the mouth. Teeth of the coronal about twenty, triangular, short, little divergent. Pores circular, somewhat irregular in size, three to four times as broad as the bars, in all three joints nearly of the same shape.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.11; breadth, a 0.05, b 0.1, c 0.12.

Habitat.—Indian Ocean, Cocos Islands, surface (Rabbe).

14. Calocyclas aspasia, n. sp.

Shell ovate, conical, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of twice the length. Thorax and abdomen nearly of the same shape as in the preceding species, but covered with longer conical spines, less numerous, and twice as long as the diameter of the subregular, circular pores. Mouth more constricted, and armed with a coronal of twelve to sixteen broad, lamellar feet, as long as the cephalis, and similar to those of Calocyclas puella (Pl. [74], fig. 5).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

15. Calocyclas monumentum, n. sp. (Pl. [73], fig. 9).

Shell nearly conical, with two very deep strictures, everywhere covered with long, bristle-shaped, divergent spines, about as long as the thorax. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 6. Cephalis nearly spherical, with a very large, three-sided pyramidal horn of twice the length. Thorax and abdomen of similar form, campanulate, with a lower cylindrical, and an upper truncate, conical part. Pores irregular, roundish, in the smaller thorax of slightly different sizes, in the larger abdomen three to four transverse rows of larger pores (six to eight in each row) are separated by numerous much smaller pores. Peristome wide open, with a coronal of twelve large, triangular, vertical feet, nearly as long as the abdomen; in the base of each foot a large, roundish, triangular pore.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.06; breadth, a 0.04, b 0.12, c 0.18.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 606. Clathrocyclas,[[223]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a simple corona of terminal feet around the dilated mouth. Abdomen dilated, truncate-conical, or discoidal. No ribs in the shell-wall.

The genus Clathrocyclas differs from the preceding closely allied Calocyclas in the dilated mouth and the flatter form of the abdomen, which is usually truncate, conical, or nearly discoidal. The conical thorax is often separated from the flat abdomen by an elegant ribbon of small quadrangular pores. The feet or teeth of the terminal corona are divergent, or even horizontally expanded, whilst in Calocyclas they are usually vertical or somewhat convergent.

Subgenus 1. Clathrocyclia, Haeckel.

Definition.—Shell highly conical, often ovate or slenderly campanulate. Cephalis commonly with a single horn.

1. Clathrocyclas principessa, n. sp. (Pl. [74], fig. 7).

Shell ovate, with two distinct strictures. Length of the three joints = 1 : 2 : 1, breadth = 1 : 2 : 2. Cephalis hemispherical, large, with a pyramidal, occipital horn of the same length. Thorax subspherical, with irregular, circular pores, about as broad as the bars. Abdomen short, widely open with a single transverse row of circular pores, and a coronal of twelve triangular, divergent feet, as long as the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.03; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Clathrocyclas basilea, (Pl. [74], fig. 6).

Shell campanulate, with two deep strictures. Length of the three joints = 2 : 5 : 3, breadth = 3 : 7 : 9. Cephalis hemispherical, with an ovate, oblique horn of the same length. Thorax hemispherical, with subregular, circular pores of the same breadth as the bars. Abdomen short, with two transverse rows of the same pores, and with a coronal of sixteen to twenty ovate, divergent feet, as long as the horn.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.03; breadth, a 0.035, b 0.07, c 0.09.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

3. Clathrocyclas fimbriata, Haeckel.

? Halicalyptra fimbriata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ii. fig. 11.

Shell campanulate, with two deep strictures. Length of the three joints = 1 : 3 : 1, breadth = 1 : 3 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax hemispherical, in the upper half hyaline, without pores, in the lower half with four to six transverse rows of subregular, circular pores. Abdomen short, suddenly dilated, with one or two transverse rows of larger ovate pores (six to eight in one row), and with a coronal of twelve to fifteen divergent, slender, curved feet, as long as the cephalis. (In the figure of Ehrenberg, seen half from below, the cephalis is not represented.)

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.02; breadth, a 0.02, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

4. Clathrocyclas collaris, n. sp. (Pl. [74], fig. 8).

Shell subconical, with two indistinct strictures. Length of the three joints = 1 : 1 : 2, breadth = 1 : 2 : 3. Cephalis hemispherical, with a triangular prismatic horn three times the length. Thorax truncate, conical, with a single transverse row of circular pores, each of which is placed in the lower end of an oblong, lanceolate, longitudinal furrow; collar composed of fifteen to twenty such furrows. Abdomen inflated, with four to six transverse rows of circular pores, and with a coronal of nine triangular, divergent feet, longer than the collar.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Clathrocyclas puella, Haeckel.

Podocyrtis puella sinensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 3.

Shell subconical, with two indistinct strictures. Length of the three joints = 1 : 1 : 2, breadth = 1 : 2 : 3. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores subregular, circular, quincuncial, in the dilated abdomen (with four to five transverse rows), twice to three times as large as in the short thorax (with two to three rows). Coronal of the wide peristome with fifteen to twenty short, triangular, divergent feet, about as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.04; breadth, a 0.02, b 0.04, c 0.06.

Habitat.—Fossil in Barbados.

6. Clathrocyclas domina, Haeckel.

Podocyrtis domina sinensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 4.

Shell subconical, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 4. Cephalis ovate, with a conical horn of the same length (and sometimes with some little accessory thorns at its base). Pores subregular, circular, quincuncial, in the dilated abdomen (with six to eight transverse rows), twice to four times as large as in the hemispherical thorax (with four to six rows). Coronal of the wide peristome with nine to twelve short, triangular, divergent feet, half as long as the cephalis (in Ehrenberg's figure incomplete).

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 3000 fathoms; also fossil in Barbados.

Subgenus 2. Clathrocycloma, Haeckel.

Definition.—Shell flatly conical, often widely campanulate, or nearly discoidal. Cephalis commonly with two or more horns.

7. Clathrocyclas alcmenæ, n. sp. (Pl. [59], fig. 6).

Shell conical, with two indistinct strictures. Length of the three joints = 2 : 10 : 1, breadth = 2 : 12 : 14. Cephalis hemispherical, with two divergent, pyramidal horns; frontal horn as long as the cephalis, occipital horn of twice the length. Thorax conical, with large hexagonal meshes, increasing gradually in size towards the short abdomen, which is represented only by a single circular girdle of small, square, abdominal pores. Coronal of the peristome with twenty to thirty triangular, divergent, nearly horizontal feet, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.01. breadth, a 0.02, b 0.12, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

8. Clathrocyclas europæ, n. sp. (Pl. [59], figs. 11, 12).

Shell conical, almost of the same form as the preceding nearly allied species, differing from it in the concave (not straight) outline of the flatter conical thorax, in the more rounded form of its pores, and in the subspherical form of the cephalis, bearing only a single conical horn of the same length. Length of the three joints = 2 : 8 : 1, breadth = 2 : 12 : 14. In fig. 11 the cephalis is broken off, so that the four cortinar pores are visible (two smaller jugular and two larger cardinal pores, separated by two coracal beams).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.01. breadth, a 0.02, b 0.12, c 0.14.

Habitat.—Mediterranean, Corfu (Haeckel), surface.

9. Clathrocyclas semeles, n. sp. (Pl. [58], fig. 5).

Shell conical-campanulate, with two distinct strictures. Length of the three joints = 2 : 8 : 1, breadth = 2 : 8 : 10. Cephalis hemispherical, with three divergent, conical horns (the caudal horn, directed downwards, much longer than the occipital and frontal horns). Pores of the thorax large, roundish. Abdomen (as in the two preceding species) with only a single circle of forty to fifty small square pores. Coronal with about the same number of short, triangular, almost horizontally divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.01. breadth, a 0.02, b 0.08, c 0.1.

Habitat.—Central Pacific, Station 271, surface.

10. Clathrocyclas danaës, n. sp. (Pl. [59], figs. 13, 14).

Shell flatly conical, with straight outline (as in Clathrocyclas alcmenæ, Pl. [59], fig. 6). Length of the three joints = 1 : 5 : 1, breadth = 2 : 8 : 1. Cephalis hemispherical, with a single, short, conical, oblique horn (broken off in the specimen figured). Pores of the thorax polygonal, increasing gradually in size towards the girdle (in three to four circles.) Abdomen nearly horizontally expanded with two rows of pores, the inner with very small and numerous square pores, the outer with twenty to thirty much larger quadrangular pores. Coronal of the peristome with the same number of short, divergent feet, alternating with the larger pores.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.02; breadth, a 0.04, b 0.15, c 0.2.

Habitat.—North Atlantic, Canary Islands (Lanzerote), Station 354, surface.

11. Clathrocyclas jonis, n. sp. (Pl. [59], fig. 9).

Shell campanulate, with two slight strictures. Length of the three joints = 1 : 5 : 2, breadth = 1 : 6 : 8. Cephalis small, hemispherical, with two divergent, conical horns of nearly equal length. Pores of the thorax polygonal, increasing in size towards the girdle; in the upper half filled up by an extremely fine and delicate cobweb-like network. Abdomen with two rows of pores, of the same shape as in the preceding species, also with equal coronal.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.03; breadth, a 0.02, b 0.12, c 0.16.

Habitat.—Central Pacific, Station 274, surface.

12. Clathrocyclas latonæ, n. sp. (Pl. [59], fig. 7).

Shell campanulate, very similar to the preceding species, but flatter and different in the larger cephalis, bearing only a single oblique horn. All the polygonal pores of the thorax are filled out by delicate cobweb-like network. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 6. Abdomen with three circular rows of quadrangular pores; first very small and numerous, second of median size, third very large. Coronal with thirty to forty short triangular feet.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.03; breadth, a 0.03, b 0.12, c 0.18.

Habitat.—Tropical Atlantic, Station 325, surface.

13. Clathrocyclas coscinodiscus, n. sp. (Pl. [58], figs. 3, 4).

Shell flatly campanulate, with two distinct strictures. Length of the three joints = 1 : 5 : 2, breadth = 1 : 8 : 10. Cephalis hemispherical, with two divergent, pyramidal horns of the same length. Thorax with concave outline, with numerous hexagonal pores, gradually increasing in size towards the girdle, except the outermost row (inside the girdle), which is composed of very small, square pores. Abdomen (outside the girdle) with three rows of pores; first with small, second with median, third with large pores. Coronal with eighty to one hundred short, divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.03; breadth, a 0.025, b 0.16, c 0.2.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

14. Clathrocyclas cassiopeiæ, n. sp. (Pl. [59], fig. 5).

Shell flatly campanulate, with two slight strictures. Length of the three joints = 2 : 4 : 3, breadth = 2 : 6 : 8. Cephalis ovate, thorny, with a pyramidal horn of the same length, and several smaller accessory horns. Thorax smooth, with irregular, polygonal pores of nearly equal size. Abdomen spiny, with three to four irregular rows of similar pores. Coronal with sixty to ninety or more irregularly and obliquely divergent feet, little larger than the abdominal spines.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.06; breadth, a 0.03, b 0.12, c 0.16.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

Genus 607. Lamprocyclas,[[224]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a double corona of solid terminal feet around the mouth. No ribs in the shell-wall.

The genus Lamprocyclas differs from Calocyclas, its ancestral form, in the duplication of the terminal corona. Usually the feet or teeth of the lower corona are convergent and curved inwards, whilst the teeth of the upper corona are divergent and curved outwards. Sometimes above the latter a third corona begins to be developed. The whole shell is more or less conical, very thick-walled, with a large and stout apical horn.

Subgenus 1. Lamprocyclia, Haeckel.

Definition.—Feet of the peristome simple, not branched.

1. Lamprocyclas nuptialis, n. sp. (Pl. [74], fig. 15).

Shell campanulate, nearly smooth, with two slight strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis ovate, with a very large, three-sided prismatic horn, nearly as long as the shell. Thorax and abdomen gradually dilated, with regular, circular, double-edged pores. Outer coronal of the peristome with twelve to fifteen divergent feet, inner with as many subvertical, triangular, little curved feet, about as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.06; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Lamprocyclas maritalis, n. sp. (Pl. [74], figs. 13, 14).

Shell campanulate, very similar to the preceding species in form and fenestration, but not so slender and with different peristome. Length of the three joints = 4 : 5 : 6, breadth = 4 : 10 : 13. Cephalis subspherical, with a very stout, pyramidal horn of twice the length, the edges of which are spirally convoluted. Outer coronal of the peristome with twelve to fifteen short, divergent feet, inner with as many convergent, longer feet.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.06; breadth, a 0.04, b 0.1, c 0.13.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Lamprocyclas deflorata, n. sp. (Pl. [74], fig. 10).

Shell ovate, smooth, with deep collar, but indistinct lumbar stricture; very similar to the two preceding species, but with different horn and peristome. Length of the three joints = 3 : 5 : 8, breadth = 3 : 10 : 13. Cephalis subspherical, with a pyramidal horn of twice the length, the three faces of which are deeply concave. Thoracic pores half as large as the abdominal, both subregular, double-edged. Outer coronal of the wide peristome with nine short, triangular, subvertical feet, inner with nine larger, horizontal feet, lying in the plane of the wide mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.08; breadth, a 0.03, b 0.1, c 0.13.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Lamprocyclas saltatricis, n. sp. (Pl. [74], fig. 16).

Shell conical, rough, with two slight strictures. Length of the three joints = 2 : 2 : 3, breadth = 1 : 4 : 6. Cephalis ovate, with a large, prismatic horn, half as long as the shell. Pores subregular, circular, not double-edged, three times as broad in the inflated abdomen as in the hemispherical thorax. Outer coronal of the wide peristome with twelve to fifteen divergent feet, inner with fifteen to twenty conical feet, which are curved inwards nearly horizontally.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.07; breadth, a 0.025, b 0.1, c 0.15.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Lamprocyclas reginæ, n. sp. (Pl. [74], figs. 11, 12).

Shell campanulate, with two slight strictures. Length of the three joints = 2 : 3 : 3, breadth = 2 : 5 : 6. Cephalis subcylindrical, with about fifteen longitudinal rows of circular pores, separated by prominent, parallel crests, and with a very large sword-like horn, nearly as long as the shell. Thorax hemispherical, smooth, with elegant, circular, hexagonally-framed pores. Abdomen dilated, with similar but larger pores, armed with hook-shaped spines. The two inferior rows of these hooks form the double coronal of the peristome; the feet of the outer are curved downwards, of the inner inwards.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.06; breadth, a 0.04, b 0.1, c 0.12.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

6. Lamprocyclas ægles, Haeckel.

Podocyrtis ægles, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B. B iv. fig. 18.

Shell campanulate, conical, thorny, with two deep strictures. Length of the three joints = 3 : 5 : 5, breadth = 3 : 8 : 11. Cephalis ovate, with a stout, three-sided prismatic horn of twice the length. Pores subregular, circular, twice as broad in the inflated abdomen as in the campanulate thorax, and four times as broad as in the cephalis. Outer coronal of the wide peristome with fifteen to twenty conical, divergent feet, inner coronal with a smaller number of vertical, parallel, divergent feet.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.05; breadth, a 0.03, b 0.08, c 0.11.

Habitat.—North Atlantic, depth 1400 fathoms (Berrymann).

Subgenus 2. Lamprocycloma, Haeckel.

Definition.—Feet of the peristome forked or branched.

7. Lamprocyclas bajaderæ, n. sp.

Shell campanulate, very similar to the preceding species, but with stronger spines on the abdomen and with different peristome. Length of the three joints = 2 : 2 : 3, breadth = 2 : 6 : 8. Cephalis equal to that of Lamprocyclas maritalis (Pl. [74], figs. 13, 14). Outer coronal of the peristome with fifteen to twenty divergent, pyramidal feet, half as long as the horn; inner coronal with as many longer, vertical feet, which are irregularly forked or branched.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.06; breadth, a 0.04, b 0.12, c 0.16.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

Genus 608. Diplocyclas,[[225]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a double corona of radial solid feet, an upper around the lumbar stricture, a lower around the mouth. No ribs in the shell-wall.

The genus Diplocyclas differs from all the other Theophormida in the possession of a double coronal of radial teeth, an upper between thorax and abdomen, and a lower around the terminal mouth of the latter; it may be regarded as an Anthocyrtis, which has formed an abdomen, and repeated the terminal armature. The cephalis bears a single or double apical horn.

1. Diplocyclas bicorona, n. sp. (Pl. [59], fig. 8).

Shell slender, campanulate. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 4. Cephalis subspherical, with two divergent horns; the occipital of the same length and forked, the frontal shorter and simple. Thorax campanulate, with six to eight transverse rows of double-edged roundish pores of increasing size. Abdomen cylindrical, with three transverse rows of large polygonal pores, and a terminal row of very small square pores. Lumbar and terminal coronals of similar shape, each with twenty to thirty short divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.025, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Diplocyclas bicincta, n. sp.

Shell campanulate, in general of the same form as, and similar fenestration to, the preceding species but not so slender, and with different proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 5 : 5. Cephalis hemispherical, with a single, conical, simple horn. Pores of the thorax hexagonal, of increasing size (in eight to ten transverse rows). Abdomen with smaller square pores (in four to six rows). The two coronals of the same shape as in Pl. [59], fig. 8.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Diplocyclas bizonalis, n. sp.

Shell subconical, with indistinct collar and distinct lumbar stricture. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with two divergent conical horns of equal size. Thorax conical, with small, irregular, double-edged pores, and a terminal corona of about nine very large pores. Abdomen truncate, conical, with three to four transverse rows of roundish, quadrangular, very large pores. Lumbar and terminal coronals of similar shape, each with twelve to fifteen triangular divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subfamily 2. Theophænida, Haeckel, 1881, Prodromus, p. 437.

Definition.—Phormocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida multiradiata clausa).

Genus 609. Hexalatractus,[[226]] n. gen.

Definition.—Theophænida (vel Tricyrtida multiradiata clausa) with six lateral wings on the abdomen.

The genus Hexalatractus, and the following genus Theophæna, represent together the small subfamily Theophænida, or those Tricyrtida in which the terminal mouth of the shell is closed by lattice-work, and six or nine lateral apophyses indicate a multiradiate structure. The shell is more or less ovate or spindle-shaped, tapering towards both poles, and resembles greatly the triradiate Rhopalocanium. It may be derived from the latter by interpolation of three secondary or interradial wings between the three primary or perradial apophyses.

1. Hexalatractus sexalatus, n. sp.

Shell ovate, smooth, with two distinct strictures, length of the three joints = 3 : 6 : 9, breadth = 4 : 9 : 8. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate; abdomen inversely conical; both with subregular, circular pores. Six divergent wings arise, beginning from the collar stricture, from the upper half of the shell, with broad triangular base; they are little curved downwards, with the convexity outside, and gradually tapering towards the distal end; the latter lies in the same horizontal plane as the basal apex of the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Stations 263, depth 2650 fathoms.

2. Hexalatractus fusiformis, n. sp. (Pl. [68], fig. 13).

Shell rough, nearly spindle-shaped, with sharp collar and slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 7. Cephalis hemispherical, with a conical horn of the same length. Thorax hemispherical with regular, circular, hexagonally-framed pores. Abdomen inversely conical, with irregular, roundish pores. From the upper half of the abdomen arise, with broad triangular base, six divergent wings, which are nearly straight, and slightly fenestrated at the base; their conical distal ends do not reach the horizontal plane, in which the basal apex of the abdomen lies.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 610. Theophæna,[[227]] Haeckel, 1881, Prodromus, p. 437.

Definition.—Theophænida (vel Tricyrtida multiradiata clausa) with nine lateral wings on the abdomen.

The genus Theophæna differs from the preceding six-radiate Hexalatractus in the possession of nine lateral wings, and may be derived from the triradiate Rhopalocanium by interpolation of six secondary wings between the three primary apophyses.

1. Theophæna corona, n. sp. (Pl. [70], fig. 12).

Shell rough, nearly spindle-shaped, with two sharp strictures. Length of the three joints = 4 : 9 : 16, breadth = 5 : 12 : 10. Cephalis hemispherical, very thick-walled, with a conical horn of the same length; both covered with numerous small dimples and spinules. Thorax campanulate; abdomen inversely conical; both with regular, circular pores. Thorax with nine thin curved ribs, which in the upper half of the abdomen arise as nine large feet, which are strongly compressed and curved (with the convexity outwards); their distal ends form nine ovate spinulate cones, and lie in the same horizontal plane as the basal apex of the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.09, c 0.16; breadth, a 0.05, b 0.12, c 0.1.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

2. Theophæna nonaria, n. sp.

Shell thorny, ovate, with two slight strictures. Length of the three joints = 1 : 4 : 5, breadth = 1 : 5 : 4. Cephalis subspherical, with a conical horn of half the length. Thorax subspherical, with regular, circular pores and conical spines. Abdomen ovate, smooth, with irregular, roundish pores. In the upper half of the thorax descend nine straight, little divergent ribs, which in the lower half become free, and represent nine slender, conical wings; their distal ends do not reach the horizontal plane in which the basal end of the abdomen lies.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.15; breadth, a 0.03, b 0.14, c 0.12.

Habitat.—South of Australia, Station 160, surface.

Family LXVII. Theocyrtida, n. fam.

Theocorida et Theocapsida, Haeckel, 1881, Prodromus, pp. 434, 436.

Definition.—Tricyrtida eradiata. Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, without radial apophyses.

The family Theocyrtida, composed of the Theocorida and Theocapsida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed, and bears no external radial apophyses. The two subfamilies differ in the shape of the terminal mouth, which in the Theocorida is a simple wide opening, in the Theocapsida closed by a lattice-plate. The phylogenetic origin of the Theocyrtida may be found either in the Podocyrtida or in the Sethocyrtida; they may have been derived from the former by reduction and loss of the three primary apophyses, or from the latter by development of an abdomen.

The number of species in this group is very large, and many belong to the most common and widely distributed Cyrtoidea. A great number of living and fossil species have already been described by Ehrenberg, the majority being disposed in his genera Lithocampe and Eucyrtidium.

The number of genera, however, is comparatively small, and their distinction difficult, since the form of the shell presents no striking differences.

It exhibits all possible passages, from a flatly expanded or nearly discoidal form with a wide open mouth, to a conical or cylindrical, and by constriction of the terminal mouth to an ovate or spindle-shaped form. By complete closure of the mouth the Theocapsida arise. In some genera remarkable traces of the original triradial structure are preserved. The most interesting of these forms is Axocorys, with an internal axial columella, which bears a number of verticils, each with three radial branches.

Synopsis of the Genera of Theocyrtida.

I. Subfamily Theocorida.

Terminal mouth of the abdomen a simple wide opening.

Abdomen gradually dilated towards the wide open mouth.Abdomen flatly expanded, discoidal.With horn,611. Theocalyptra.
No horn,612. Cecryphalium.
Abdomen conical.One horn,613. Theoconus.
Two or more horns,614. Lophoconus.
Abdomen cylindrical, of nearly equal breadth throughout its whole length. Mouth truncate.A single apical horn on the cephalis.Thorax and abdomen of equal breadth,615. Theocyrtis.
Thorax much broader than the tubular abdomen,616. Theosyringium.
Two horns or a bunch of horns on the cephalis,617. Lophocyrtis.
No horn on the cephalis,618. Tricolocampe.
Abdomen ovate or inversely conical. Mouth more or less constricted.A single apical horn on the cephalis.Shell-cavity without an internal columella,619. Theocorys.
Shell-cavity with an axial columella,620. Axocorys.
Two horns or a bunch of horns on the cephalis,621. Lophocorys.
No horn on the cephalis,622. Theocampe.

II. Subfamily Theocapsida.

Terminal mouth closed by a lattice-plate.

No latticed septum between thorax and abdomen.An apical horn,623. Theocapsa.
No horn on the cephalis,624. Tricolocapsa.
A complete latticed septum between thorax and abdomen,625. Phrenocodon.

I. Subfamily Theocorida.

Terminal mouth of the abdomen a simple wide opening.

Abdomen gradually dilated towards the wide open mouth.
Abdomen flatly expanded, discoidal.
With horn,
611. Theocalyptra.
No horn,
612. Cecryphalium.
Abdomen conical.
One horn,
613. Theoconus.
Two or more horns,
614. Lophoconus.
Abdomen cylindrical, of nearly equal breadth throughout its whole length. Mouth truncate.
A single apical horn on the cephalis.
Thorax and abdomen of equal breadth,
615. Theocyrtis.
Thorax much broader than the tubular abdomen,
616. Theosyringium.
Two horns or a bunch of horns on the cephalis,
617. Lophocyrtis.
No horn on the cephalis,
618. Tricolocampe.
Abdomen ovate or inversely conical. Mouth more or less constricted.
A single apical horn on the cephalis.
Shell-cavity without an internal columella,
619. Theocorys.
Shell-cavity with an axial columella,
620. Axocorys.
Two horns or a bunch of horns on the cephalis,
621. Lophocorys.
No horn on the cephalis,
622. Theocampe.

II. Subfamily Theocapsida.

Terminal mouth closed by a lattice-plate.

No latticed septum between thorax and abdomen.
An apical horn,
623. Theocapsa.
No horn on the cephalis,
624. Tricolocapsa.
A complete latticed septum between thorax and abdomen,
625. Phrenocodon.

Subfamily 1. Theocorida, Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocyrtida with the basal mouth of the shell open (vel Tricyrtida eradiata aperta).

Genus 611. Theocalyptra,[[228]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with discoidal or flatly expanded abdomen. Cephalis with a single apical horn, or with two divergent horns.

The genus Theocalyptra, and the following closely allied genus Cecryphalium, differ from all the other Theocorida in the flattened form of the cap-shaped or nearly discoidal shell. The abdomen specially is quite flat, often horizontally expanded, and like the marginal brim of a flat hat. They may be derived from the Dicyrtida Sethocephalus by the development of an abdomen, or from Corocalyptra by loss of the collar wings. The network is usually very delicate, as in the latter. The cephalis of Theocalyptra bears one or two horns.

1. Theocalyptra veneris, n. sp.

Shell flatly campanulate, very delicate and fragile, very similar to Eucecryphalus agnesæ (Pl. [59], fig. 3), but without collar spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 7 : 9. Cephalis hemispherical, with a single bristle-shaped horn of twice the length. Thorax subconical, separated from the flatter abdomen by a deep stricture, with thin bars, and large, subregular, hexagonal meshes, increasing in size towards the smooth mouth-edge.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.04; breadth, a 0.025, b 0.15, c 0.1.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, many stations, surface.

2. Theocalyptra orci, Haeckel.

Halicalyptra orci, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. x. figs. 9, 10.

Shell flatly campanulate, very similar to the preceding species in general form and fenestration, but flatter and smaller, with different proportions. Length of the three joints = 7 : 2 : 1, breadth = 1 : 6 : 8. Cephalis hemispherical, very small, with two divergent, bristle-shaped horns of the same length. Abdomen nearly horizontally expanded.

Dimensions.—Length of the three joints, a 0.015, b 0.04, c 0.01; breadth, a 0.02, b 0.12, c 0.16.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

3. Theocalyptra discoides, Haeckel.

Cycladophora discoides, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 4.

Shell flatly campanulate, similar to the two preceding species, but not so delicate, with thicker bars, and roundish, not hexagonal meshes. Length of the three joints = 1 : 2 : 2, breadth = 3 : 6 : 9. Cephalis large, trilobed, with a short, oblique horn of half the length. Thorax campanulate, conical, separated from the abdomen by a circle of smaller pores and a deep stricture. Abdomen flat, discoidal, with three circles of larger pores.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.06, b 0.12, c 0.18.

Habitat.—Fossil in Barbados.

4. Theocalyptra cornuta, Haeckel.

Carpocanium cornutum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ii. fig. 9.

Halicalyptra cornuta, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 5, pl. i. figs. 13, 14.

Lophophæna cornuta, Haeckel, 1862, Monogr. d. Radiol., p. 299.

Shell campanulate-conical, with two sharp strictures. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 5. Cephalis subspherical, with two stout, pyramidal, divergent horns of twice the length. Thorax campanulate, with eight to ten transverse rows of roundish or nearly square pores, increasing in size towards the abdomen, which is flatly expanded, nearly discoidal, separated by a circle of smaller pores; the last circle of pores (on the margin) is larger.

Dimensions.—Length of the three joints, a 0.025, b 0.09, c 0.03; breadth, a 0.03, b 0.12, c 0.16.

Habitat.—Arctic Ocean, Kamtschatka (Bailey), Greenland (Ehrenberg).

Genus 612. Cecryphalium,[[229]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with discoidal or flatly expanded abdomen. Cephalis without horn.

The genus Cecryphalium has the same flat, conical, or nearly discoidal shell as the preceding Theocalyptra, its ancestral genus, but differs from it in the complete absence of horns on the cephalis.

1. Cecryphalium lamprodiscus, n. sp. (Pl. [58], fig. 2).

Shell flatly conical, with two slight strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 7 : 11. Cephalis roundish, very small. Thorax conical, with straight lateral outline; its pores irregular, polygonal, increasing in size towards the girdle. Abdomen little flatter than the thorax, forming its direct prolongation, with five to six circular, concentric rows of pores; the first row formed by sixty to eighty very large, oblongish, quadrangular pores, the second row by very small, the third again by larger pores; the outmost rows by very small and numerous pores.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.14, c 0.22.

Habitat.—Central Pacific, Station 272, surface.

2. Cecryphalium sestrodiscus, n. sp. (Pl. [58], fig. 1).

Shell very flat, subconical, nearly discoidal, with two distinct strictures. Length of the three joints = 1 : 2 : 1, breadth = 1 : 8 : 10. Cephalis kidney-shaped, very small. Thorax flat, campanulate, with curved lateral outline; its pores irregular, polygonal, increasing in size towards the girdle. Abdomen horizontally expanded, like the brim of a hat, with five to six concentric, circular rows of pores, the pores of the inner rows twice to three times as large as those of the outer rows. (The inner circle of large, oblongish, quadrangular pores, characteristic of the preceding species, is here divided into three concentric rings by two circular hoops.)

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.02, b 0.15, c 0.2.

Habitat.—Central Pacific, Station 274, surface.

Genus 613. Theoconus,[[230]] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with conical abdomen, gradually dilated towards the wide open mouth. Cephalis with a single horn.

The genus Theoconus, and the following closely allied Lophoconus, differ from the other Theocorida in the conical or campanulate form of the shell; the abdomen is a truncated cone, gradually dilated towards the terminal mouth. The latter is usually truncated, widely open, sometimes with a slightly constricted peristome. The cephalis of Theoconus bears a single apical horn.

Subgenus 1. Theocorax, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Theoconus zancleus, Haeckel.

Eucyrtidium zancleum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 41, Taf. vi. figs. 1-3.

Eucyrtidium zancleum, Haeckel, 1862, Monogr. d. Radiol., p. 321.

Shell bell-shaped, nearly conical, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 6. Cephalis nearly spherical, with a stout, straight, pyramidal horn of the same length. Thorax hemispherical. Abdomen gradually increasing in breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, circular, regular, four times as broad as the thin bars.

Dimensions.—Length of the three joints, a 0.027, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.18.

Habitat.—Mediterranean (Messina, Naples, Nice, &c.).

2. Theoconus ægæus, Haeckel.

Eucyrtidium ægæum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31; Mikrogeol., 1854, Taf. xxxv. a, xix. a, fig. 5.

Eucyrtidium ægæum, Haeckel, 1862, Monogr. d. Radiol., p. 329.

Shell flatly bell-shaped, nearly conical. Length of the three joints = 2 : 5 : 3; breadth = 1 : 7 : 8. Cephalis ovate, with a stout, straight, pyramidal horn of the same length. Thorax flat, bell-shaped. Abdomen with increasing breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, regular, circular, three times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.03; breadth, a 0.016, b 0.07, c 0.08.

Habitat.—Mediterranean (Coast of Greece and Sicily), surface.

3. Theoconus zanguebaricus, Haeckel.

Eucyrtidium zanguebaricum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. ix. fig. 22.

Shell bell-shaped. Length of the three joints = 1 : 2 : 1, breadth = 1 : 3 : 4. Cephalis ovate, with a straight, pyramidal horn of half the length. Thorax hemispherical, without collar stricture, but with evident girdle stricture. Abdomen dilated towards the wide truncated mouth. Pores regular, hexagonal, of nearly equal size and form, four to six times as broad as the thin bars.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.03; breadth, a 0.024, b 0.09, c 0.11.

Habitat.—Indian Ocean (off Zanzibar), Pullen, depth 2200 fathoms.

4. Theoconus campanulatus, Haeckel.

? Eucyrtidium campanulatum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 241.

Eucyrtidium campanulatum, Haeckel, 1862, Monogr. d. Radiol., p. 329.

Shell bell-shaped, smooth. Length of the three joints = 2 : 3 : 7, breadth = 3 : 7 : 10. Cephalis small, spherical, with a short, conical, oblique horn of the same length. Thorax hemispherical, with an external girdle stricture, prolonged into the truncated, barrel-shaped abdomen, which is a little constricted at the very wide mouth. Pores small and very numerous, regular, circular, twice to three times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.07; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—North Atlantic, Station 352, surface.

5. Theoconus orthoconus, n. sp.

Shell perfectly conical, smooth. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 4. Cephalis hemispherical, with a strong, straight, conical horn of the same length. Thorax conical, without external girdle stricture, prolonged into the truncated, conical abdomen, which is gradually dilated into a very wide mouth. Pores small, of nearly equal size and similar form, of the same breadth as the bars.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, at different depths.

Subgenus 2. Theocorbis, Haeckel.

Definition.—Pores of the thorax and of the abdomen of different sizes or dissimilar forms.

6. Theoconus jovis, n. sp. (Pl. [69], fig. 4).

Shell bell-shaped, nearly conical. Length of the three joints = 5 : 6 : 7, breadth = 4 : 10 : 14. Cephalis nearly cylindrical, large, little curved, with a very large, oblique, pyramidal horn, as long as the two first joints together. Thorax and the broader abdomen irregularly bell-shaped, dilated towards the wide mouth. Pores circular, somewhat irregularly disposed, gradually increasing in size towards the mouth.

Dimensions.—Length of the three joints, a 0.05, b 0.06, c 0.07; breadth, a 0.04, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

7. Theoconus junonis, n. sp. (Pl. [69], fig. 7).

Shell nearly conical. Length of the three joints = 4 : 5 : 8, breadth = 3 : 8 : 11. Cephalis ovate, with a large apical opening at the base of the vertical compressed horn, which has about the same length. Thorax and the broader abdomen together conical, gradually dilated towards the wide mouth. Thorax with a bosom-like protuberance on one side. Pores circular, gradually increasing in size.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.11.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

8. Theoconus longicornis, n. sp.

Shell conical, thorny. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis nearly spherical, with a very large, cylindrical, perpendicular, straight horn, once and a half to twice as long as the whole shell. Thorax conical. Abdomen nearly hemispherical, with wide open mouth. Pores circular, four to six times as broad in the thick-walled spiny abdomen as in the thin-walled rough thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.09, c 0.18.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil in Barbados.

9. Theoconus ampullaceus, Haeckel.

Lithocampe ampullacea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iv. fig. 1.

Theocorys ampullacea, Haeckel, 1881, Prodromus, p. 434.

Shell bell-shaped, nearly conical, thorny. Length of the three joints = 3 : 4 : 10; breadth = 4 : 8 : 15. Cephalis subspherical, with a stout lateral horn of the same length. Thorax hemispherical, rough. Abdomen subspherical, widely truncated at both poles, spiny. Pores regular, circular, three to four times as broad in the thick-walled abdomen as in the thin-walled thorax. (Differs from the similar preceding species in the smaller horn and the two deeper strictures of the shell.)

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.08, c 0.15.

Habitat.—Fossil in Barbados.

10. Theoconus amplus, Haeckel.

? Podocyrtis ampla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 7.

? Podocyrtis ampla, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxiii. fig. 16.

? Eucyrtidium amplum, Ehrenberg, 1873, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 248.

Shell conical, smooth, with two broad internal annular septa. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a very large, straight, conical horn of the same breadth, which is as long as the conical thorax. Pores regular, circular, twice as broad in the truncate, gradually dilated abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.03, b 0.12, c 0.15.

Habitat.—Fossil in Barbados.

11. Theoconus ariadnes, n. sp.

Shell conical, nearly bell-shaped, smooth. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis subspherical, with a conical spine of about the same length. Thorax hemispherical, thin-walled. Abdomen conical, slightly constricted at the wide open mouth. Pores regular, circular, twice as large in the thick-walled abdomen as in the thin-walled thorax.

Dimensions.—Length of the three joints, a 0.018 to 0.022, b 0.03 to 0.035, c 0.06 to 0.07; breadth, a 0.015 to 0.02, b 0.04 to 0.06, c 0.07 to 0.09.

Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific Oceans, common, surface.

12. Theoconus dionysius, Haeckel.

Thyrsocyrtis dionysia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 5.

Thyrsocyrtis jacchia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 7.

Shell bell-shaped, smooth. Length of the three joints = 1 : 3 : 5, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical, irregularly denticulate horn of twice or thrice the length. Thorax inflated, nearly spherical, truncate at both poles, separated by a deep stricture from the cephalis, as well as from the conical abdomen, which is dilated gradually towards the wide mouth. Pores in the thorax subregular, circular, in the abdomen twice to four times larger, and irregular.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.02, b 0.08, c 0.1.

Habitat.—Fossil in Barbados.

13. Theoconus laterna, n. sp.

Shell conical, smooth. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 4. Cephalis small, ovate, with a strong, pyramidal, vertical horn three times the length. Thorax hemispherical, with subregular, circular, hexagonally-framed pores. Abdomen truncate, conical, with only fifteen to twenty very large, irregular, polygonal pores, which are separated by very thick bars of the same breadth as the horn.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.07, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

14. Theoconus ficus, Haeckel.

Eucyrtidium ficus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 19.

Theocorys ficus, Haeckel, 1881, Prodromus, p. 434.

Shell conical, pear-shaped, smooth. Length of the three joints = 1 : 5 : 20, breadth = 2 : 10 : 25. Cephalis very small, ovate, with a conical, straight horn three times the length. Thorax quite conical, with solid wall, without pores. Abdomen very large, nearly spherical, truncate at both poles, little constricted at the very wide mouth; its pores subregular, circular, about three times as broad as the bars. (This species is intermediate between the genera Theoconus and Theocorys.)

Dimensions.—Length of the three joints, a 0.01, b 0.05, c 0.2; breadth, a 0.02, b 0.1, c 0.25.

Habitat.—Fossil in Barbados.

Genus 614. Lophoconus,[[231]] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with conical abdomen gradually dilated towards the wide open mouth. Cephalis with two or more horns or a corona of horns.

The genus Lophoconus has the same conical shell with truncate mouth as Theoconus, and differs from it only in the armature of the cephalis, bearing either two large divergent horns (usually a larger occipital and a smaller frontal horns), or a bunch or corona of numerous divergent horns.

1. Lophoconus antilope, Haeckel.

Eucyrtidium antilope, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 18.

Shell conical, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 8, breadth = 2 : 4 : 8. Cephalis hemispherical, with two divergent, pyramidal horns of twice the length. Thorax campanulate. Abdomen gradually dilated towards the wide open mouth. Pores very small and numerous, regular, hexagonal.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.12; breadth, a 0.025, b 0.07, c 0.12.

Habitat.—Indian Ocean; between Aden and Socotra (Haeckel); Zanzibar (Pullen).

2. Lophoconus hexagonalis, n. sp.

Shell campanulate, conical, spiny, with two sharp strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with numerous conical spines of different sizes, the largest of twice the length. Thorax campanulate, with smaller spines. Abdomen inflated, dilated towards the wide mouth. Pores large, three or four times as broad as the bars, subregular, hexagonal.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Lophoconus cornutella, n. sp.

Shell slender, conical, smooth, without external strictures, but with two internal, annular septa. Length of the three joints = 1 : 2 : 6, breadth = 1 : 2 : 4. Cephalis ovate, with two stout, divergent, conical horns of three times the length. Thorax and abdomen together conical, gradually dilated towards the wide truncate mouth. Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.02, b 0.04, c 0.08.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

4. Lophoconus apiculatus, Haeckel.

Eucyrtidium apiculatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 10.

Shell campanulate, conical, thorny, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis subspherical, with a bunch of eight to twelve divergent, conical horns, the largest of which are longer than the cephalis. The regular, circular pores are in the campanulate thorax scarcely half as broad as in the truncate, gradually dilated abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.025, b 0.06, c 0.08.

Habitat.—Fossil in Barbados.

5. Lophoconus cervus, Haeckel

? Eucyrtidium cervus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 21.

Shell conical, smooth, without external stricture, but with two internal annular septa. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis campanulate, with two to six divergent, partly ramified horns. Pores in the thorax regular, circular, in the abdomen three to four times as large, regular, hexagonal.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.12.

Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface (? Zanzibar, 2200 fathoms, Pullen).

6. Lophoconus rhinoceros, n. sp. (Pl. [69], fig. 2).

Shell campanulate, conical, rough, with two sharp strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with numerous very small pores, and two stout, divergent, pyramidal horns, the major of which is longer, the minor shorter, than the cephalis. Thorax campanulate, with small, regular, circular pores. Abdomen inflated, with thickened margin at the wide open mouth, and with irregular, roundish pores, twice to four times as broad as those of the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.04, b 0.09, c 0.12.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 615. Theocyrtis,[[232]] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, and wide open truncate mouth. Cephalis with a single horn.

The genus Theocyrtis and the three following closely allied genera differ from the other Theocorida in the cylindrical form of the slender abdomen, which is of equal breadth nearly throughout its whole length. The terminal mouth is wide open, usually truncate, and of the same breadth; sometimes slightly constricted. The cephalis of Theocyrtis bears a single horn.

Subgenus 1. Theocorypha, Haeckel.

Definition.—Pores of the thorax and abdomen of nearly equal size and similar form.

1. Theocyrtis trachelius, Haeckel.

Eucyrtidium trachelius, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 8.

Shell thin-walled and very fragile, smooth. Length of the three joints = 2 : 8 : 7, breadth = 2 : 9 : 8. Cephalis subspherical, with a straight, conical horn of the same length, separated by a slender neck from the inflated, subspherical thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, hexagonal, of equal size, four to six times as broad as the thin, thread-like bars.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.07; breadth, a 0.02, b 0.09, c 0.08.

Habitat.—Tropical Pacific, many Stations (200, 224, 271, &c.), surface, and in various depths.

2. Theocyrtis barbadensis, Haeckel.

Eucyrtidium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 7.

Shell thin-walled, smooth. Length of the three joints = 2 : 4 : 5, breadth, 2 : 5 : 4. Cephalis ovate or conical, with a strong, conical horn, without external stricture, dilated into the campanulate thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, circular, quincuncially disposed, of about the same breadth as the bars.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.08.

Habitat.—Fossil in the Tertiary rocks of Barbados.

3. Theocyrtis cylindrica, Haeckel.

Eucyrtidium cylindricum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 1.

Shell elongate, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a thick, pyramidal horn of the same length (the edges of the horn giving to it the appearance of being composed of two converging spines). Thorax truncated, conical. Abdomen perfectly cylindrical, much elongated. Pores subregular, circular, twice as broad as the bars, quincuncially disposed. Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Tropical Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

4. Theocyrtis elegans, Haeckel.

Eucyrtidium elegans, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 12.

? Eucyrtidium pusillum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 6

Shell slender, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 7, breadth = 1 : 3 : 3. Cephalis subconical, with a small conical horn. Thorax campanulate, conical. Abdomen cylindrical, very slender. Pores subregular, circular, small, disposed in transverse rows, three in the thorax, six to eight in the abdomen. Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.01, b 0.02, c 0.07; breadth, a 0.015, b 0.03, c 0.03.

Habitat.—Fossil in Barbados and Sicily.

5. Theocyrtis paupera, Haeckel.

Eucyrtidium pauperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 13.

Shell slender, cylindrical, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a stout conical horn of twice the length. Thorax truncate, conical. Abdomen cylindrical. Pores very small, regular, circular, disposed in transverse rows, one or two in the thorax, three to five in the abdomen. (Distance between the rows twice as great as in the preceding nearly related species.) Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.01, b 0.02, c 0.06; breadth, a 0.015, b 0.03, c 0.03.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados and Sicily.

6. Theocyrtis microtheca, Haeckel.

Eucyrtidium microtheca, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 10.

Eucyrtidium hillaby, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 8.

Shell cylindrical, a little rough. Length of the three joints = 1 : 3 : 4, breadth = 1 : 3 : 3. Cephalis subspherical, with a small conical horn. Thorax hemispherical or campanulate. Abdomen cylindrical, with wide open truncate mouth. Pores subregular, circular, quincuncially disposed, of medium size, rudimentary or wanting in the cephalis.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.03 to 0.05, c 0.05 to 0.08; breadth, a 0.02 to 0.025, b 0.05 to 0.06, c 0.05 to 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms; also fossil in Barbados.

Subgenus 2. Theocorusca, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or forms.

7. Theocyrtis macroceros, n. sp. (Pl. [69], fig. 13).

Shell almost cylindrical, smooth. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 4. Cephalis hemispherical, with a very large cylindrical horn, once or twice as long as the shell. Thorax truncate, hemispherical. Abdomen cylindrical, only slightly contracted towards both ends. Two girdle strictures deep. Pores small, subregular, circular, more irregular and twice to three times as large in the abdomen as in the thorax, disposed in transverse rows, five to six in the thorax, eight to ten in the abdomen.

Dimensions.—Length of the three joints, a 0.02 to 0.03, b 0.04 to 0.05, c 0.1 to 0.12; breadth, a, 0.04, b 0.07, c 0.08.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms; also fossil in Barbados.

8. Theocyrtis ptychodes, n. sp. (Pl. [69], fig. 8).

Shell almost cylindrical, smooth. Length of the three joints = 1 : 3 : 3, breadth = 2 : 4 : 4. Cephalis hemispherical, with a large, conical, curved horn of twice the length. Thorax very large, inflated, campanulate, thick-walled. Abdomen cylindrical, with a thin folded wall (like a petticoat), the thickness of which decreases gradually towards the wide truncate mouth. Pores subregular, circular, and quincuncially disposed in the two first joints, irregular and larger in the abdomen, forming longitudinal series between the folds.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.11; breadth, a 0.05, b 0.12, c 0.12.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

9. Theocyrtis aspera, Haeckel.

Eucyrtidium asperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. viii. fig. 15.

Shell almost cylindrical, with rough or thorny surface. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 5. Cephalis subspherical, small, with a short conical horn. Thorax hemispherical, inflated. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax subregular, circular, quincuncially disposed, in the abdomen irregular roundish, two to four times as large.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.06 to 0.07, c 0.08 to 0.1; breadth, a 0.02, b 0.1, c 0.1.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; fossil in Barbados.

10. Theocyrtis proserpinæ, n. sp.

Shell almost cylindrical, smooth. Length of the three joints = 3 : 6 : 9, breadth = 2 : 8 : 7. Cephalis subspherical, with a stout conical horn. Thorax campanulate. Abdomen cylindrical. Pores regular, circular, quincuncially disposed, double-edged in the thorax, and three to four times as large as in the cephalis and the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.02, b 0.08, c 0.07.

Habitat.—North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.

11. Theocyrtis oenophila, Haeckel.

Thyrsocyrtis oenophila, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 8.

Shell in the apical half conical, in the lower cylindrical. Length of the three joints = 2 : 5 : 6, breadth = 3 : 8 : 7. Cephalis subspherical, with a large prismatic horn, which is bulbous at the base, and armed with three teeth at the distal apex. Thorax conical, constricted at the base, with subregular, circular, quincuncial pores. Abdomen cylindrical, with a coronal of nine large roundish pores beyond the lumbar stricture, and two to four succeeding transverse rows of irregular, roundish, smaller pores. Mouth widely open, truncated.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

Genus 616. Theosyringium, Haeckel,[[233]] 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, which is much narrower than the inflated thorax, and forms a slender, narrow tube, with truncated mouth. Cephalis with a single horn.

The genus Theosyringium differs from the closely allied Theocyrtis, its ancestral form, in the wide inflated thorax, which is much broader than the narrow tubular abdomen. The mouth of the latter is small and truncate.

1. Theosyringium tibia, n. sp. (Pl. [68], fig. 4).

Shell rough, very slender, with two distinct strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 2 : 1. Cephalis ovate, with a conical horn of the same length. Thorax ellipsoidal. Abdomen cylindrical, as long as the two former joints together. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.03, b 0.06, c 0.02.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

2. Theosyringium pipetta, n. sp. (Pl. [68], fig. 5).

Shell rough, inflated, with two sharp strictures. Length of the three joints = 2 : 7 : 9, breadth = 2 : 7 : 2. Cephalis conical, with a slender horn of half the length. Thorax subglobose. Abdomen cylindrical, as long as the two former joints together. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.09; breadth, a 0.02, b 0.07, c 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Theosyringium siphonium, n. sp.

Shell rough, inflated, with two deep strictures. Length of the three joints = 1 : 3 : 3, breadth = 1 : 2 : 1. Cephalis subspherical, with a stout pyramidal horn of twice the length. Thorax broad ovate. Abdomen slender, inversely conical, as long as the thorax, and one-third as broad as the base. Pores subregular, circular, hexagonally framed, (Similar to Eusyringium conosiphon, Pl. [78], fig. 10, but only with two strictures and three joints.)

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.1; breadth, a 0.03, b 0.07, c 0.025.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Theosyringium tubulus, Haeckel.

Eucyrtidium tubulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 6.

Shell smooth, slenderly spindle-shaped, with two slight strictures. Length of the three joints = 2 : 10 : 8, breadth = 3 : 6 : 3. Cephalis hemispherical, hyaline, with a stout, pyramidal horn of the same length. Thorax spindle-shaped. Abdomen inversely conical, half as long as the thorax prolonged into a slender, cylindrical tube. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.08; breadth, a 0.03, b 0.06, c 0.03.

Habitat.—Fossil in Barbados.

Genus 617. Lophocyrtis,[[234]] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, and wide open truncate mouth. Cephalis with two horns, or a bunch of horns.

The genus Lophocyrtis differs from its ancestral form Theocyrtis only in the armature of the cephalis, bearing instead of a single horn either two divergent horns, or a bunch, or coronal of numerous spines. The slender abdomen is in both genera cylindrical, with wide open mouth.

1. Lophocyrtis holothuria, n. sp.

Shell smooth, slender, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 3. Cephalis hemispherical, with a bunch of five divergent, conical horns, the middle of which is larger and vertical, nearly as long as the thorax. Thorax campanulate, half as long as the cylindrical abdomen. Mouth truncate. Pores regular, circular, quincuncial. (Similar to Theocyrtis cylindrica, but with different cephalis and thorax.)

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.1; breadth, a 0.04, b 0.07, c 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Lophocyrtis stephanophora, Haeckel.

Eucyrtidium stephanophorum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin p. 72, Taf. viii. fig. 14.

Shell smooth, slender, with deep collar and indistinct lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis subspherical, with very small circular pores, and a corona of three to nine short conical spines. Thorax campanulate, with regular, circular pores, which are half or one-third as broad as those of the cylindrical abdomen.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.09; breadth, a 0.025, b 0.06, c 0.06.

Habitat.—Fossil in Barbados.

3. Lophocyrtis synapta, n. sp. Pl. [68], fig. 15.

Shell spiny, with two sharp strictures. Length of the three joints = 5 : 10 : 6, breadth = 4 : 9 : 7. Cephalis large, ovate, with numerous (twenty to thirty or more) conical, radially divergent spines of different sizes, the largest about as long as the cephalis. Thorax subconical, with numerous short, conical, divergent spines, which are directed downwards. Abdomen smooth, cylindrical. The irregular, polygonal pores are separated by thin bars, and in the thorax are twice to four times as broad as in the first and last joints.

Dimensions.—Length of the three joints, a 0.05, b 0.1, c 0.06; breadth, a 0.04, b 0.09, c 0.07.

Habitat.—Indian Ocean, Maldive Islands (Haeckel), surface.

4. Lophocyrtis coronata, Haeckel.

Eucyrtidium coronatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 9.

Shell smooth, cylindrical, with two deep strictures. Length of the three joints = 4 : 3 : 4, breadth = 4 : 5 : 4. Cephalis subspherical, large, of about the same size and form as the thorax, with a coronal of four to eight short, conical spines on the apex. Pores in the two first joints irregular, roundish, twice to four times as broad as the small, circular pores of the cylindrical abdomen, which are disposed in four to eight transverse rows.

Dimensions.—Length of the three joints, a 0.04, b 0.03, c 0.04; breadth, a 0.04, b 0.05, c 0.04.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms; fossil in Barbados.

5. Lophocyrtis biaurita, Haeckel.

Eucyrtidium biauritum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 8.

Eucyrtidium biauritum, Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 540, Taf. xxxiii. fig. 38, a-f.

Shell smooth, with two distinct strictures. Length of the three joints = 1 : 6 : 3, breadth = 2 : 5 : 4. Cephalis small, hemispherical, hyaline, with two large, divergent, curved horns of three times the length. Thorax ovate, with few small, widely scattered pores. Abdomen cylindrical, without pores.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth, a 0.02, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

Genus 618. Tricolocampe,[[235]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with cylindrical abdomen, and wide open truncate mouth. Cephalis without horn.

The genus Tricolocampe differs from its ancestral genus, Theocyrtis, in the loss of the cephalic horn; it has the same cylindrical form of the slender abdomen, and a wide open terminal mouth of the same breadth. The whole shell is more or less cylindrical, (sometimes conical in the upper part), with two distinct external strictures, or internal annular septa.

Subgenus 1. Tricolocampium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Tricolocampe cylindrica, n. sp. (Pl. [66], fig. 21).

Shell nearly cylindrical, smooth. Length of the three joints = 2 : 3 : 15, breadth = 3 : 4 : 5. Cephalis hemispherical, with numerous very small pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, circular pores, disposed regularly in transverse rows, three to four rows in the thorax, ten to twelve in the abdomen. Mouth wide open, not constricted.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.15; breadth, a 0.03, b 0.04, c 0.05.

Habitat.—Central Pacific, Stations 265 to 274, depth 2350 to 2925 fathoms.

2. Tricolocampe pupa, Haeckel.

Eucyrtidium pupa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 16.

Shell nearly cylindrical, smooth. Length of the three joints = 2 : 2 : 8, breadth = 2 : 3 : 3. Cephalis subspherical, with four larger pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, very small pores, disposed regularly in transverse rows, two rows in the thorax, eight to ten in the abdomen. Mouth wide open, a little constricted.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.08; breadth, a 0.02, b 0.03, c 0.03.

Habitat.—Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.

3. Tricolocampe polyzona, n. sp. (Pl. [66], fig. 19).

Shell nearly cylindrical, thick-walled. Length of the three joints = 4 : 4 : 12, breadth = 8 : 9 : 9. Cephalis obtuse, conical. Thorax barrel-shaped. Abdomen in the middle part a little constricted. Pores very numerous, subregular, disposed regularly in transverse rows, six to eight in the cephalis, eight to ten in the thorax, twelve to fifteen in the abdomen. Mouth rather constricted, only half as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.12; breadth, a 0.08, b 0.09, c 0.09.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms; also fossil in the Nicobars and in Barbados.

4. Tricolocampe stenozona, n. sp. (Pl. [66], fig. 20).

Shell nearly cylindrical, thin-walled. Length of the three joints = 5 : 4 : 9, breadth = 6 : 8 : 9. Form of the three joints and disposition of their pores nearly equal to the preceding species; but the proportion of the joints is different, the shell more delicate, and the mouth more widely open, and nearly as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.05, b 0.04, c 0.09; breadth, a 0.06, b 0.08, c 0.09.

Habitat.—North Pacific, Station 256, depth 2950 fathoms.

5. Tricolocampe amphizona, n. sp. (Pl. [66], fig. 17).

Shell mitre-shaped, very thick-walled. Length of the three joints = 2 : 1 : 1, breadth nearly uniform. Cephalis obtuse, conical, as long as the two other cylindrical joints together (probably composed of several united joints). Pores subregular, disposed in transverse rows, six to eight in the cephalis, two in the thorax, and two in the abdomen. Mouth widely open.

Dimensions.—Length of the three joints, a 0.04, b 0.02, c 0.02; breadth, a 0.04, b 0.05, c 0.05.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

6. Tricolocampe panthera, Haeckel.

Eucyrtidium panthera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 18.

Shell mitre-shaped or nearly cylindrical, thick-walled. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 2. Cephalis subspherical. Thorax campanulate. Abdomen cylindrical. Pores in all three joints irregular, roundish, of different sizes, irregularly disposed. Mouth widely open, truncated, not constricted.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.04 to 0.05, c 0.06 to 0.08; breadth about a 0.02, b and c 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific; also fossil in Barbados.

Subgenus 2. Tricolocamptra, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or forms.

7. Tricolocampe urnula, n. sp. (Pl. [66], fig. 22).

Shell cylindrical, with obtuse conical apex, smooth. Length of the three joints = 2 : 3 : 10, breadth = 2 : 3 : 6. Cephalis subspherical. Thorax barrel-shaped. Abdomen cylindrical with slightly constricted wide mouth. Pores irregular, roundish, three to four times as broad in the abdomen as in the thorax, irregularly disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1; breadth, a 0.025, b 0.035, c 0.06.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

8. Tricolocampe doliolum, n. sp.

Shell cylindrical, with hemispherical apex, rough. Length of the three joints = 1 : 3 : 5, breadth = 1 : 2 : 3. Cephalis spherical. Thorax and abdomen cylindrical, of nearly equal breadth. Mouth widely open, not constricted. Pores irregular, roundish, in the abdomen three to four times as large as in the thorax, disposed in oblique rows.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.16; breadth, a 0.03, b 0.05, c 0.09.

Habitat.—Fossil in Barbados.

9. Tricolocampe cingulata, n. sp.

Shell subcylindrical, with obtuse conical apex, thick-walled. Length of the three joints = 2 : 3 : 11, breadth = 3 : 7 : 8. Cephalis hemispherical, not separated externally from the short conical thorax, but with internal collar septum. Abdomen cylindrical, with wide open, non-constricted mouth. Pores in the thorax narrow, obliquely ascending, in the abdomen twice as large, circular, arranged in ten to twelve regular transverse rows, separated by slight strictures. Lumbar septum nearly complete.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1 to 0.12; breadth, a 0.03, b 0.07, c 0.08.

Habitat.—Fossil in Barbados, and in Tertiary rocks of Sicily; living in the depths of the Atlantic and Central Pacific, Station 348, depth 2450 fathoms; Station 268, depth 2900 fathoms.

10. Tricolocampe arcta, Haeckel.

? Eucyrtidium arctum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 33.

? Lithocampe arcta, Haeckel, 1862, Monogr. d. Radiol., p. 317.

Shell subcylindrical, with obtuse conical apex. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 2. Cephalis subspherical. Thorax campanulate, separated by a deep collar, but a slight lumbar stricture. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax narrow, obliquely ascending, in the abdomen half as large, very small, and densely disposed in six to eight regular transverse rows.

Dimensions.—Length of the three joints, a 0.022, b 0.045, c 0.09; breadth, a 0.026, b 0.05, c 0.05.

Habitat.—Central Pacific, Station 266 to 274, depth 2350 to 2925 fathoms.

Genus 619. Theocorys,[[236]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis with a single horn.

The genus Theocorys and the two following closely allied genera, united formerly with Eucyrtidium, differ from the preceding Theocorida in the constriction of the peristome, so that the inflated abdomen is broader than the terminal mouth. They represent, therefore, the transition to the Theocapsida, with closed mouth. The abdomen is commonly more or less ovate or barrel-shaped, sometimes inversely conical. The cephalis of Theocorys bears a single apical horn.

Subgenus 1. Theocoronium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Theocorys turgidula, Haeckel.

Eucyrtidium turgidulum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 13.

Shell slender, ovate, with two deep strictures, very fragile and thin-walled. Length of the three joints = 2 : 5 : 7, breadth = 2 : 6 : 6. Cephalis subspherical, with a pyramidal horn of the same length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores very numerous, regular hexagonal, three to four times as broad as the bars.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.07; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—Tropical Pacific (Philippine Sea), Stations 206 and 224, surface.

2. Theocorys veneris, n. sp. (Pl. [69], fig. 5).

Shell inversely ovate, with two deep strictures, smooth. Length of the three joints = 2 : 5 : 6, breadth = 3 : 7 : 6. Cephalis hemispherical, with a slender conical horn of twice the length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores regular, circular, twice as broad as the bars, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.07, c 0.06.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; many Stations, surface.

3. Theocorys cretica, Haeckel.

Eucyrtidium creticum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. xi. fig. 23.

Shell ovate, thin-walled, smooth, with two deep strictures. Length of the three joints = 2 : 4 : 4, breadth = 3 : 6 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax and abdomen nearly hemispherical, inflated, united by the opposite bases of the hemispheres. Constricted mouth only one-third as broad as the abdomen. Pores very small and numerous, regular, circular, of the same breadth as the bars, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Mediterranean, Crete, Corfu, surface.

4. Theocorys ovata, n. sp. (Pl. [69], fig. 16).

Shell quite ovate, thick-walled, smooth, without external strictures. Length of the three joints = 2 : 2 : 9. breadth = 3 : 5 : 7. Cephalis conical, with a thick conical horn of the same length. Thorax and abdomen gradually dilated towards the base, and then hemispherical, constricted. Mouth scarcely one-third as broad as the abdomen, prolonged into a short tube. Pores regular, circular, disposed in transverse rows, two to three in the cephalis, two to three in the thorax, eight to ten in the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.09; breadth, a 0.03, b 0.05, c 0.07.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 3000 fathoms.

5. Theocorys plutonis, n. sp. (Pl. [69], fig. 1).

Shell ovate, thick-walled, smooth, with two slight strictures. Length of the three joints = 2 : 5 : 4, breadth = 4 : 7 : 6. Cephalis hemispherical, with a conical, oblique horn of the same length. Thorax and abdomen only slightly inflated, gradually decreasing towards the wide, little constricted mouth. Pores subregular, circular, much larger in the abdomen and the lower half of the thorax than in the upper half and the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.04; breadth, a 0.04, b 0.07, c 0.06.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

6. Theocorys scolopax, Haeckel.

Eucyrtidium scolopax, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 5.

Shell slender, inversely ovate, smooth. Length of the three joints = 1 : 3 : 3, breadth = 1 : 4 : 4. Cephalis subspherical, with a long, slightly curved horn, half as long as the whole shell. Thorax campanulate. Abdomen inversely ovate, twice as broad as the constricted mouth (incomplete in Ehrenberg's figure).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.06; breadth, a 0.02, b 0.08, c 0.08.

Habitat.—Fossil in Barbados.

Subgenus 2. Theocorythium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of different sizes or dissimilar forms.

7. Theocorys dianæ, n. sp. (Pl. [69], fig. 11).

Shell almost ovate, with two deep strictures. Length of the three joints = 3 : 6 : 8, breadth = 3 : 9 : 8. Cephalis subspherical, with a slender, pyramidal horn of three times the length. Thorax conical, constricted at the base. Abdomen bottle-shaped. Pores in the thorax irregular, polygonal, in the abdomen subregular, circular, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—North Pacific, Station 253, surface.

8. Theocorys hyalothorax, n. sp.

Shell slender, ovate, with two deep strictures. Length of the three joints = 6 : 9 : 8, breadth = 7 : 12 : 11. Cephalis subspherical, with numerous densely-placed circular pores, and with a pyramidal, slender horn of the same length. Thorax hemispherical, hyaline, without any pores. Abdomen ovate, twice as broad as the constricted mouth, with two to four widely distant, transverse rows of small, circular pores.

Dimensions.—Length of the three joints, a 0.024, b 0.036, c 0.032; breadth, a 0.028, b 0.048, c 0.044.

Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.

9. Theocorys bachabunda, Haeckel.

Thyrsocyrtis bachabunda, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 4.

Shell inversely ovate, with two distinct strictures. Length of the three joints = 2 : 5 : 9, breadth = 3 : 9 : 8. Cephalis subspherical, small, with a large cylindrical horn, which is half as long as the whole shell, and armed with spines at the conical apex. Thorax conical, inflated, with small, subregular, circular, quincuncial pores. Abdomen inversely ovate, with irregular, roundish, pores of larger and smaller sizes mixed, gradually lessening towards the constricted mouth.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—Fossil in Barbados.

10. Theocorys attenuata, Haeckel.

Eucyrtidium attenuatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 16.

Shell inversely ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 2 : 5 : 5, breadth = 2 : 7 : 6. Cephalis hemispherical, with a short, oblique, conical horn. Thorax inflated, campanulate, with small, regular, circular, quincuncial pores. Abdomen inversely conical, with irregular pores of larger and smaller sizes mixed, gradually lessening towards the truncated mouth.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.05; breadth, a 0.025, b 0.07, c 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

11. Theocorys obliqua, n. sp. (Pl. [69], fig. 10).

Shell inversely ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 3 : 7 : 4, breadth = 4 : 9 : 8. Cephalis hemispherical, with a stout, pyramidal, oblique horn of the same length. Thorax and abdomen together ovate, gradually lessening towards the constricted mouth, which is only half as broad. Pores irregular, roundish, in the thorax twice to four times as broad as in the abdomen. Both joints are separated by an oblique, internal, lumbar septum, which in some specimens observed was more oblique than in that figured; some specimens had a very irregular form.

Dimensions.—Length of the three joints, a 0.025 to 0.03, b 0.06 to 0.07, c 0.03 to 0.04; breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

12. Theocorys alauda, Haeckel.

Eucyrtidium alauda, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 4.

Shell nearly spindle-shaped, decreasing from the thicker middle towards both ends. Length of the three joints = 1 : 3 : 8, breadth = 1 : 4 : 5. Cephalis subspherical, with a strong, conical horn of three times the length. Thorax campanulate, with numerous regular, circular, quincuncial pores. Abdomen inversely ovate, slender, twice as broad as the truncated mouth, with irregular, roundish pores, three to four times as large as those of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.16; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Fossil in Barbados and in Tertiary rocks of Sicily.

13. Theocorys apollinis, n. sp. (Pl. [69], fig. 3).

Shell ovate, with two deep strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 5 : 7. Cephalis subspherical, with a large, straight, cylindrical horn, about as long as the whole shell (in the specimen figured this is broken off). Thorax truncate, conical. Abdomen subglobose, truncate on both poles, twice as broad as the constricted mouth. Pores quincuncial, subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.05; breadth, a 0.02, b 0.05, c 0.07.

Habitat.—South Atlantic, Station 332, surface.

14. Theocorys sphærophila, Haeckel.

Eucyrtidium sphærophilum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. viii. fig. 16.

Shell almost ovate, rough, with two slight strictures. Length of the three joints = 2 : 7 : 10, breadth = 3 : 8 : 12. Cephalis subspherical, with a strong, conical horn of the same length. Thorax nearly spherical, with subregular, circular pores of different sizes. Abdomen ovate, truncate at both poles, nearly twice as broad as the constricted mouth, with very large, subregular, hexagonal pores, four to six times as broad as the bars, in three to four transverse, and ten to twelve longitudinal rows.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

15. Theocorys tuberculata, n. sp.

Shell almost ovate, tuberculate, with deep collar, but slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 11. Cephalis hemispherical, with a cylindrical horn of twice the length. Thorax hemispherical, with regular, circular, double-edged, quincuncial pores, between which conical tubercles occur. Abdomen truncate, ovate, twice as broad as the constricted mouth, with regular, circular, hexagonally-framed pores, three to four times as broad as those of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.11.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; fossil in Barbados.

16. Theocorys martis, n. sp.

Shell slender, ovate, with two deep strictures. Length of the three joints = 3 : 6 : 18, breadth = 4 : 8 : 12. Cephalis small, hemispherical, with a very large, sword-shaped broad horn, nearly as long as the whole shell. Thorax hemispherical, honey-comb like, with regular, circular, hexagonally-framed pores. Abdomen ovate, with irregular, roundish, very large pores, four to six times as broad as the bars, and as the pores of the thorax. Constricted mouth half as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.18; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

17. Theocorys mercurii, n. sp.

Shell ovate, conical, with two slight strictures. Length of the three joints = 1 : 3 : 7, breadth = 2 : 4 : 7. Cephalis hemispherical, with a broad pyramidal horn of the same length. Thorax campanulate, with longitudinal series of small, regular, circular pores, separated by divergent crests. Abdomen nearly spherical, one and a half times as broad as the constricted mouth, which is prolonged into a thin, solid, cylindrical peristome. Pores of the abdomen regular, circular, hexagonally framed, three to four times as broad as the bars, and as the pores of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.15; breadth, a 0.04, b 0.09, c 0.15.

Habitat.—South Atlantic, Station 338, depth 1990 fathoms.

18. Theocorys minervæ, n. sp. (Pl. [69], fig. 14).

Shell ovate, conical, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a large pyramidal horn as long as the thorax, and with small, circular pores. Thorax rough, with regular, quincuncial, circular pores, three to four times as large as those of the cephalis. Abdomen barrel-shaped, with irregular, roundish pores of very different sizes, six very large pores immediately beyond the lumbar stricture, and four to five rows of pores, which are twice to four times as large as those of the thorax. Mouth truncated, with thickened margin, two-thirds as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.12, c 0.16; breadth, a 0.04, b 0.16, c 0.2.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 620. Axocorys,[[237]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, including an internal vertical axial rod, which bears three divergent radial spines or verticils of three branches, and is prolonged into an apical horn.

The genus Axocorys contains only a single but very remarkable species, and may, perhaps, represent a peculiar group, which has closer relations to the Plectoidea than to the other Tricyrtida. The pyriform three-jointed shell has neither lateral nor terminal free appendages, but possesses a very large apical horn, and an inner prolongation of this, an axial rod, which bears some triradiate verticils of branched spines. The original ancestral forms of this remarkable genus are probably Plagoniscus and Plectaniscus (pp. [912] and [924]).

1. Axocorys macroceros, n. sp. (Pl. [68], figs. 1, 1a).

Shell pear-shaped, with two distinct strictures. Length of the three joints = 2 : 3 : 16, breadth = 3 : 6 : 16. Cephalis hemispherical, with few small pores. From its apex arises vertically a very long three-sided prismatic horn with denticulate edges, three to four times as long as the shell. An inner thin prolongation of the horn descends vertically nearly to the mouth, and bears on its basal end three verticils of branched spines, each verticil with three divergent forked spines (fig. 1a). Pores regular, circular, in the subspherical abdomen three times as large as in the hemispherical thorax. The constricted mouth is scarcely broader than the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.16; breadth a 0.03, b 0.06, c 0.16.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 621. Lophocorys,[[238]] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, broader than the constricted mouth. Cephalis with two divergent horns, or with a bunch of horns.

The genus Lophocorys differs from its ancestral form, Theocorys, only in the armature of the cephalis, bearing either two divergent horns, or a corona of several radial horns. In two species there are four horns on the apex, a larger vertical (occipital) horn being surrounded by three smaller, upwards divergent horns.

1. Lophocorys astrocephala, n. sp. (Pl. [69], fig. 9).

Shell smooth, inversely ovate, with deep collar and slight lumbar stricture. Length of the three joints = 3 : 7 : 6, breadth = 4 : 11 : 10. Cephalis subspherical, stellate, densely covered with numerous (ten to twenty or more) divergent, large, slenderly conical horns, the longest of which reach the length of the shell. Thorax campanulate, with small, regular, circular pores. Abdomen tapering towards the constricted mouth, in the upper half with the same pores, in the lower half with smaller, scarce pores, or nearly hyaline.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.06; breadth, a 0.04, b 0.11, c 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Lophocorys acanthocephala, Haeckel.

Eucyrtidium acanthocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 8.

Shell rough, bottle-shaped, with two slight strictures. Length of the three joints = 5 : 11 : 7, breadth = 4 : 12 : 10. Cephalis conical, with a large pyramidal horn of the same length, and three smaller divergent accessory horns at the base of the three edges of the latter. Thorax campanulate, nearly as long as the tapering abdomen (which in the figure of Ehrenberg is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.05, b 0.11, c 0.07; breadth, a 0.04, b 0.12, c 0.1.

Habitat.—Fossil in Barbados.

3. Lophocorys bicornis, Haeckel.

Eucyrtidium bicorne, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 7.

Shell smooth, almost spindle-shaped, with two slight strictures. Length of the three joints = 2 : 8 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with two stout, pyramidal, divergent horns of twice the length. Thorax ovate, with seven to eleven transverse rows of small, regular, circular pores (often very scarce in the upper half). Abdomen with two to four transverse rows of the same pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.03; breadth, a 0.03, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

4. Lophocorys quadricornis, n. sp.

Shell rough, slenderly ovate, with two distinct strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 4 : 3. Cephalis ovate, with four very stout, three-sided prismatic horns; the largest is as long as the thorax and vertical upon the apex, the three smaller are as long as the cephalis and diverge upwards from the base of the former. Thorax ovate, with large, irregular, roundish pores, which are three to four times as broad as the small, circular pores of the first and the third joint. Constricted mouth half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.045, b 0.085, c 0.04; breadth, a 0.035, b 0.075, c 0.06.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

5. Lophocorys bovicornis, n. sp. (Pl. [69], fig. 12).

Shell rough, subovate, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with two divergent, curved horns of different lengths. Thorax campanulate, with small, circular pores. Abdomen subspherical, truncate at both poles, twice as broad as the constricted mouth, thorny, with very large, circular pores, four to six times as broad as those of the smaller thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.12.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Genus 622. Theocampe,[[239]] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis without horn.

The genus Theocampe differs from the two preceding genera in the absence of horns on the cephalis, and may, therefore be derived from Theocorys by reduction of the apical horn. It bears to the latter the same relation as Tricolocampe does to Theocyrtis.

Subgenus 1. Theocampana, Haeckel.

Definition.—Pores of the thorax and the abdomen of nearly equal size and similar form.

1. Theocampe ehrenbergii, Haeckel.

Dictyomitra ehrenbergii, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 82, Taf ii. fig. 5.

Shell ovate, smooth. Length of the three joints = 2 : 3 : 13, breadth = 4 : 7 : 12. Cephalis hemispherical. Thorax truncate, conical. Abdomen inflated, nearly spherical, twice as broad as the constricted mouth. Pores of nearly equal size and form, small, regular, circular.

Dimensions.—Length of the three joints, a 0.014, b 0.018, c 0.076; breadth, a 0.023, b 0.044, c 0.073.

Habitat.—Fossil in the chalk of Northern Germany; Brunswick (Zittel).

2. Theocampe pirum, Haeckel.

Eucyrtidium pirum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. x. fig. 14.

Eucyrtidium excellens, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 31.

Shell ovate, smooth. Length of the three joints = 3 : 5 : 15, breadth = 6 : 10 : 16. Cephalis hemispherical. Thorax truncate conical. Abdomen inflated, subspherical, three times as broad as the constricted mouth. Pores of nearly equal size, regular, circular in the thorax alternating, in the abdomen disposed in five to six transverse, widely distant rows.

Dimensions.—Length of the three joints, a 0.015, b 0.025 c 0.075; breadth, a 0.03, b 0.05, c 0.08.

Habitat.—Fossil in the Tertiary rocks of Barbados.

3. Theocampe stenostoma, n. sp. (Pl. [66], fig. 23).

Shell about ovate, smooth. Length of the three joints = 3 : 4 : 3, breadth = 6 : 8 : 9. Cephalis hemispherical, large. Thorax and abdomen short, barrel-shaped. Both strictures deep. Abdomen three times as broad as the constricted mouth. Pores of equal size, regular, circular, disposed in oblique rows.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.03; breadth, a 0.06, b 0.08, c 0.09.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Theocampe nucula, Haeckel.

Eucyrtidium nucula, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 29, Taf. vii. fig. 19.

Shell nearly ovate, rough. Length of the three joints = 3 : 5 : 3, breadth = 4 : 7 : 6. Cephalis hemispherical, large. Thorax and abdomen inflated. Both strictures deep. Thorax broader than the short abdomen, and twice as broad as the constricted mouth. Pores of equal size, regular, circular, regularly disposed in transverse rows: three in the cephalis, six in the thorax, and three in the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.03; breadth, a 0.04, b 0.07, c 0.06.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil in Barbados.

5. Theocampe cryptoprora, Haeckel.

Eucyrtidium cryptoprora, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 14.

Shell ovate, thin-walled, smooth, without external strictures, but with two distinct internal annular septa. Length of the three joints = 2 : 7 : 4, breadth = 3 : 7 : 6. Cephalis, large, subspherical, hyaline; its lower half hidden in the upper part of the campanulate thorax. Mouth little constricted, nearly as broad as the truncate abdomen. All pores equal, small, regular, circular.

Dimensions.—Length of the three joints, a 0.025, b 0.07, c 0.04; breadth, a 0.03, b 0.07, c 0.06.

Habitat.—Tropical Pacific, Stations 225 to 265, in various depths.

6. Theocampe ovulum, n. sp.

Shell perfectly ovate, thick-walled, smooth, without external strictures, but with two broad, internal septa. Length of the three joints = 2 : 3 : 10, breadth = 3 : 6 : 8. Cephalis and thorax together obtuse, conical, with obliquely ascending pores. Abdomen inflated, twice as broad as the constricted mouth, with ten to twelve transverse rows of pores. All pores equal, small, regular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1; breadth, a 0.03, b 0.06, c 0.08.

Habitat.—Fossil in Tertiary rocks of Barbados and Sicily.

7. Theocampe cassis, Haeckel.

Eucyrtidium cassis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 20.

Shell bottle-shaped, thin-walled, with slight collar, but deep lumbar stricture. Length of the three joints = 3 : 8 : 6, breadth = 2 : 7 : 7. Cephalis ovate. Thorax campanulate. Abdomen inflated, twice as broad as the constricted mouth. Pores equal, regular, circular, disposed in quincuncial rows.

Dimensions.—Length of the three joints, a 0.03, b 0.08. c 0.06; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Tropical Pacific (Philippines), Station 206, depth 2100 fathoms.

Subgenus 2. Theocamptra, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or dissimilar forms.

8. Theocampe sphærothorax, n. sp. (Pl. [66], fig. 25).

Shell almost ovate, rough. Length of the three joints = 2 : 5 : 10, breadth = 3 : 8 : 8. Cephalis hemispherical. Thorax nearly spherical, truncate. Abdomen ovate, twice as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, in the abdomen twice as broad as in the thorax, and four times as broad as in the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

9. Theocampe versipellis, Haeckel.

Eucyrtidium versipellis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 14.

Shell slenderly ovate, rough. Length of the three joints = 3 : 5 : 13, breadth = 4 : 8 : 9. Cephalis subspherical, without pores. Thorax hemispherical. Abdomen inflated, twice as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, in the abdomen three times as broad as in the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.13; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

10. Theocampe megalopora, Haeckel.

Eucyrtidium megaloporum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 19.

Shell almost ovate, with two distinct strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 6 : 4. Cephalis hemispherical. Thorax ovate, inflated. Abdomen inversely ovate, two to three times as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, twice as broad in the large thorax as in the smaller abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.06, c 0.04.

Habitat.—Central Pacific, Station 267, depth 2700 fathoms.

11. Theocampe collaris, n. sp. (Pl. [66], fig. 18).

Shell almost ovate, with two distinct strictures. Length of the three joints = 3 : 3 : 6, breadth = 4 : 5 : 7. Cephalis obtuse conical, with five or six transverse rows of small pores. Thorax truncate conical, with longitudinal furrows, each of which contains a single pore. Abdomen inflated, with five or six distant, transverse rows of small, circular pores.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.06; breadth, a 0.04, b 0.05, c 0.07.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

12. Theocampe gemmata, Haeckel.

Eucyrtidium gemmatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 6.

Shell slenderly ovate, smooth, with two internal annular septa. Length of the three joints = 1 : 1 : 4, breadth = 1 : 2 : 3. Cephalis campanulate, nearly as large as the truncate, conical thorax, both with small, irregular, obliquely descending pores. Abdomen broader, twice as broad as the constricted mouth, with numerous longitudinal ribs, alternating with single rows of small, circular pores. (This and the following allied species approach to Cycladophora, by the abdominal ribs.)

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.07; breadth, a 0.025, b 0.035, c 0.045.

Habitat.—Fossil in Barbados.

13. Theocampe costata, n. sp. (Pl. [66], fig. 24).

Shell almost ovate, with two sharp strictures. Length of the three joints = 2 : 4 : 8, breadth = 3 : 5 : 7. Cephalis hemispherical. Thorax twice as large, also hemispherical, both with regular, circular, quincuncial pores. Abdomen broader, with numerous longitudinal ribs, alternating with longitudinal rows of larger pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.05, c 0.07.

Habitat.—Indian Ocean, Sunda Straits (Rabbe), surface.

14. Theocampe cryptocephala, Haeckel.

Eucyrtidium cryptocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 11.

Shell ovate, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, its lower half hidden in the campanulate thorax. Abdomen subspherical, twice as broad as the constricted mouth. Pores subregular, circular, quincuncial, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.07; breadth, a 0.025, b 0.07, c 0.09.

Habitat.—Fossil in Barbados.

Subfamily 2. Theocapsida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Theocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida eradiata clausa).

Genus 623. Theocapsa,[[240]] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa), with an apical horn, and a terminal lattice-plate on the mouth.

The genus Theocapsa, and the two following genera, represent together the small subfamily of Theocapsida, or of those Tricyrtida in which the mouth is closed by a lattice-plate, and external radial appendages are wanting. Theocapsa may be derived from Theocorys by fenestration of the constricted mouth.

Subgenus 1. Theocapsetta, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or somewhat larger; pores of both nearly equal in size and similar in form.

1. Theocapsa aristotelis, n. sp. (Pl. [66], fig. 6).

Shell subovate, smooth, with two distinct strictures. Length of the three joints = 2 : 6 : 7, breadth = 3 : 8 : 8. Cephalis hemispherical, with a conical, slender horn of about the same length. Thorax and abdomen nearly equal in size, thin-walled, smooth, with small, regular, circular pores of equal size. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.07; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Mediterranean (Gibraltar), Atlantic (Canary Islands), surface.

2. Theocapsa plinii, n. sp.

Shell subovate, smooth, with two indistinct strictures. Length of the three joints = 2 : 5 : 6, breadth = 3 : 7 : 7. Cephalis hemispherical, with a pyramidal, thick horn of about the same length. Thorax and abdomen of nearly equal size, thick-walled, rough, with large, regular, circular, double-edged pores of equal size (twice as large and half as numerous as in the similar preceding species).

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.07, c 0.07.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

3. Theocapsa democriti, n. sp. (Pl. [66], fig. 8).

Shell slender, ovate, spiny, with two distinct strictures. Length of the three joints = 3 : 5 : 6, breadth = 4 : 7 : 7. Cephalis ovate, with numerous slender horns of the same length. Thorax and abdomen with small, irregular, roundish pores of nearly equal size, armed with scattered slender spines, half as long as the cephalic horns. Basal pole hemispherical, rounded.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.06; breadth, a 0.04, b 0.07, c 0.07.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Theocapsa galeni, n. sp.

Shell broadly ovate, spiny, with two deep strictures. Length of the three joints = 2 : 7 : 6, breadth = 3 : 8 : 7. Cephalis hemispherical, with two conical, divergent horns of the same length. Thorax and abdomen with large, irregular, roundish pores of nearly equal size, armed with numerous short spines, not larger than the pores. Basal pole conical, pointed.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.06; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Theocapsilla, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or somewhat larger; pores of the two different in size or form.

5. Theocapsa wottonis, n. sp. (Pl. [66], fig. 11).

Shell subovate, rough, with two deep strictures. Length of the three joints = 3 : 7 : 5, breadth = 3 : 9 : 8. Cephalis subspherical, with regular, circular, hexagonally-framed pores, and with a stout pyramidal horn of the same length. Thorax conical, with subregular, circular, double-edged pores. Abdomen hemispherical, smaller and thinner walled, with irregular, somewhat oblong pores. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.05; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

6. Theocapsa gessneri, n. sp.

Shell broadly ovate, with two deep strictures. Length of the three joints = 3 : 9 : 5, breadth = 4 : 10 : 4. Cephalis hemispherical, with a slender, conical horn of the same length. Thorax subspherical, with small, regular, circular pores. Abdomen inversely conical, with few large, somewhat oblong pores. Basal pole acute.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.05; breadth, a 0.04, b 0.1, c 0.04.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

7. Theocapsa aldrovandi, n. sp.

Shell slender, inversely ovate, with two slight strictures. Length of the three joints = 3 : 8 : 14, breadth = 4 : 11 : 8. Cephalis subglobular, with a conical horn of the same length. Thorax also subglobular, papillate, with regular, circular, hexagonally-framed pores. Abdomen inversely conical, slender, with very small and numerous, subregular, circular pores. Basal pole ovate, pointed.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.14; breadth, a 0.04, b 0.11, c 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Theocapsa malpighii, n. sp. (Pl. [66], fig. 15).

Shell inversely ovate, with two distinct strictures. Length of the three joints = 3 : 8 : 11, breadth = 4 : 9 : 8. Cephalis hemispherical, with a conical horn of the some length Thorax hemispherical, thorny, with very small circular pores, surrounded by large, regular, hexagonal frames. Abdomen inversely campanulate, with larger circular pores, and longitudinal ribs. Basal pole blunt, conical.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.11, breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 3. Theocapsomma, Haeckel.

Definition.—Thorax much smaller than the abdomen, pores of the two nearly equal in size and similar in form.

9. Theocapsa linnæi, n. sp. (Pl. [66], fig. 13).

Shell slender, subcylindrical, rough with two slight strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 4. Cephalis hemispherical, with a pyramidal horn of twice the length (sometimes, as in the specimen figured, one or two small accessory horns occur at its base). Thorax hemispherical, thick-walled. Abdomen nearly cylindrical, twice as long as the thorax, thin-walled, with a hemispherical, rounded basal pole. The specimen figured is an abnormal one, with some deformities on the irregular abdomen; in numerous other specimens the abdomen is cylindrical, regular. Pores of the thorax and abdomen equal, very small and numerous, regular, circular, three to four times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.05 to 0.06, c 0.1 to 0.12; breadth, a 0.03, b 0.06 to 0.07, c 0.07 to 0.08.

Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific Oceans; many Stations at various depths.

10. Theocapsa forskalii, n. sp. (Pl. [66], fig. 9).

Shell slender, subcylindrical, smooth, with two slight strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 2. Cephalis hemispherical, with a conical horn of half the length. Abdomen three times as long as the thorax, of the same breadth, with the same irregular, roundish pores, large and small intermingled. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.09; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—North Atlantic, Canary Islands, Station 353, depth 2965 fathoms.

11. Theocapsa wolffii, n. sp. (Pl. [66], fig. 14).

Shell slender, spindle-shaped very thick-walled, rough, without external strictures, but with two broad internal girdles. Length of the three joints = 2 : 3 : 15, breadth = 4 : 5 : 7. Cephalis with a short horn of the same length, conical. Abdomen five times as long as the thorax, with the same subregular, circular pores. Basal pole inversely conical, with some larger, elongate pores.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.15; breadth, a 0.04, b 0.05, c 0.07.

Habitat.—Mediterranean, Crete, depth 1620 fathoms (Spratt).

12. Theocapsa pallasii, n. sp.

Shell subovate, thorny, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a pyramidal horn of the same length. Thorax and abdomen with subregular, circular pores of medium size. Basal pole hemispherical. (Differs from Theocapsa mülleri, Pl. [66], fig. 7, mainly in the larger number and smaller size of the regular, quincuncial pores.)

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

Subgenus 4. Theocapsura, Haeckel.

Definition.—Thorax much smaller than the abdomen, pores of the two different in size or form.

13. Theocapsa lamarckii, n. sp. (Pl. [66], fig. 16).

Shell slenderly ovate, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of twice the length. Thorax conical, with regular, circular pores. Abdomen three times longer, with subregular, hexagonal pores of twice the size. Basal pole hemispherical, with very large, irregular, roundish pores.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.14; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

14. Theocapsa cuvieri, n. sp. (Pl. [66], fig. 10).

Shell slenderly spindle-shaped, thorny, with two slight strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 3 : 3. Cephalis subspherical, with a conical horn of the same length. Thorax conical, spiny, with regular, circular, double-edged pores. Abdomen thinner-walled, inversely conical, with irregular, roundish pores. Basal pole acute, with a bunch of larger spines.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.02, b 0.05, c 0.06.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

15. Theocapsa baerii, n. sp.

Shell slenderly spindle-shaped, smooth with two indistinct strictures. Length of the three joints = 1 : 2 : 8, breadth = 2 : 3 : 4. Cephalis hemispherical, with a thick conical horn of the same length. Abdomen four times as long as the thorax. Pores in the thorax small and numerous, regular, circular, in the abdomen twice as large, and irregularly roundish. Basal pole inversely conical, acute. (Differs from Theocapsa wolffii, Pl. [66], fig. 14, mainly in the shape of the pores.)

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.12; breadth, a 0.03, b 0.04, c 0.06.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

16. Theocapsa rathkei, n. sp.

Shell slenderly conical, with two slight strictures. Length of the three joints = 1 : 2 : 10, breadth = 2 : 4 : 15. Cephalis small, with a large, conical horn of three times the length. Thorax small, thorny, with small irregular, roundish pores. Abdomen very large, as long and as broad as the thorax, with irregular polygonal or roundish, very large pores, the margin of which is finely denticulate. Basal pole truncate, rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.2; breadth, a 0.04, b 0.08, c 0.3.

Habitat.—Fossil in Barbados.

17. Theocapsa schwannii, n. sp.

Shell slenderly ovate, or pear-shaped, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 2 : 4 : 7. Cephalis subspherical, small, with a stout, pyramidal horn of three times the length. Cavity of the thorax subspherical, its thick wall with small, regular, circular, hexagonally-framed pores. Abdomen very thick-walled, with crested bars, and very large, irregular, roundish pores. Basal pole rounded, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.14, breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

18. Theocapsa mülleri, n. sp. (Pl. [66], fig. 7).

Shell slenderly ovate, or pear-shaped, spiny, with two indistinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a stout, pyramidal horn of the same length, and with a variable number of smaller accessory horns. Pores irregular, roundish, three to four times as broad in the inflated abdomen as in the thorax. Basal pole hemispherical, spiny.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.09.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

19. Theocapsa sarsii, n. sp.

Shell pear-shaped, with two indistinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 4. Cephalis with a thick horn of the same length, conical. Abdomen subspherical, very thick-walled, its pores regular, circular, twice as broad as the bars, and three times as broad as those of the thorax. Basal pole flat, rounded.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.12; breadth, a 0.05, b 0.11, c 0.15.

Habitat.—Fossil in Barbados.

20. Theocapsa darwinii, n. sp. (Pl. [66], fig. 12).

Shell pear-shaped, with two distinct strictures. Length of three joints = 1 : 1 : 5, breadth = 1 : 2 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with small, regular, circular pores. Abdomen broad, ovate, with larger, regular, circular, hexagonally-framed pores. Basal pole hemispherical.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.2; breadth, a 0.04, b 0.08, c 0.2.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

Genus 624. Tricolocapsa,[[241]] Haeckel.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa) without apical horn, with a terminal lattice-plate on the mouth.

The genus Tricolocapsa differs from the preceding Theocapsa in the loss of the apical horn, and exhibits therefore to it the same relation that Theocampe bears to Theocorys. In some species (Pl. [66], figs. 1, 3) a small tube begins to be developed on the cephalis, and these may perhaps be separated as a peculiar genus, Tricolopera.

Subgenus 1. Tricolocapsula, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or larger.

1. Tricolocapsa theophrasti, n. sp. (Pl. [66], fig. 1).

Shell slenderly ovate, with two slight strictures. Length of the three joints = 2 : 8 : 5, breadth = 3 : 7 : 5. Cephalis hemispherical, with a larger, tube-like, cervical pore at the collar stricture. Thorax very thick-walled, with irregular, roundish, double edged pores, smaller than the bars between them. Abdomen smaller, inversely campanulate-conical, with very irregular pores. Basal pole acute.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.05; breadth, a 0.03, b 0.07, c 0.05.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Tricolocapsa dioscoridis, n. sp. (Pl. [66], fig. 3).

Shell short and broad, with two deep strictures. Length of the three joints = 3 : 5 : 4, breadth = 4 : 7 : 5. Cephalis hemispherical, with a larger, tube-like, cervical pore above the collar stricture. Thorax very broad, with irregular, large and spare, roundish pores. Abdomen much smaller, inversely conical, with smaller pores. Basal pole obtuse.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.04; breadth, a 0.04, b 0.07, c 0.05.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Tricolocapsa linnæi, n. sp. (Pl. [66], fig. 5).

Shell short and broad, with two deep strictures. Length of the three joints = 1 : 4 : 2, breadth = 1 : 4 : 2. Cephalis hemispherical. Thorax thick-walled, inflated, with subregular, circular, double-edged pores. Abdomen much smaller, thin-walled, with irregular, polygonal pores. Basal pole hemispherical, rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.05; breadth, a 0.03, b 0.08, c 0.05.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

4. Tricolocapsa decandollei, n. sp. (Pl. [66], fig. 4).

Shell subovate, with two sharp strictures. Length of the three joints = 2 : 2 : 2, breadth = 3 : 4 : 3.5. Cephalis campanulate. Thorax broader, ring-shaped. Abdomen inversely hemispherical. All three joints of the same length, thick-walled, with the same regular and peculiar reticulation, the small circular pores being surrounded by square, elevated frames.

Dimensions.—Length of the three joints, a 0.07, b 0.07, c 0.07; breadth, a 0.10, b 0.14, c 0.12.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Tricolocapsium, Haeckel.

Definition.—Thorax much smaller than the abdomen.

5. Tricolocapsa brownii, n. sp.

Shell ovate, very thick-walled, with two indistinct strictures. Length of the three joints = 2 : 4 : 7, breadth = 3 : 7 : 10. Cephalis flat, hemispherical. Thorax truncate, conical. Abdomen inflated, inversely hemispherical. Pores regular, circular, of the same breadth as the bars, hexagonally-framed, twice as large in the abdomen as in the thorax. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.07; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—Fossil in Barbados.

6. Tricolocapsa schleidenii, n. sp. (Pl. [66], fig. 2).

Shell subconical, with two deep strictures. Length of the three joints = 2 : 3 : 6, breadth = 3 : 5 : 6. Cephalis subspherical. Pores subregular, circular, arranged in transverse girdles, three in the broad thorax, six in the subglobular abdomen. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.03, b 0.05, c 0.06.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 625. Phrenocodon,[[242]] n. gen.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa) with an apical horn, and a lattice-plate between thorax and abdomen.

The genus Phrenocodon differs from the two preceding genera in the remarkable circumstance, that the basal lattice-plate closes not the terminal mouth itself, but the constricted opening between thorax and abdomen. It may therefore be regarded as a Sethocapsa, which has developed a third, open, abdominal joint. The cephalis bears an apical horn.

1. Phrenocodon clathrostomium, n. sp. (Pl. [70], figs. 7, 8).

Shell campanulate-conical, with two deep strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 10 : 14. Cephalis hemispherical, with an oblique curved horn of the same length. Thorax subconical, with polygonal, roundish pores, increasing in size towards the girdle. A perfect fenestrated diaphragm, with irregular, roundish pores of very different sizes, separates the thorax from the abdomen. The latter is composed of three parallel, circular rings, which are connected by fifteen to twenty radial beams. As the middle ring is larger than the two others, the beams between the large quadrangular pores are divergent in the upper, convergent in the lower girdle. Short prolongations of the divergent beams form a coronal around the middle ring (compare fig. 7 profile, fig. 8 from below).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Phrenocodon diaphragma, n. sp.

Shell campanulate-conical, very similar to that of the preceding species, but with abdomen and proportions different. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 4. Abdomen cylindrical, with two or three transverse rows of large quadrangular meshes (fifteen to twenty in each row), without the characteristic inflexion of the preceding species, and without the coronal.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.034; breadth, a 0.02, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Section IV. STICHOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., p. 280, 312 (Pls. [75]-[80]).

Stichocyrtida et Tetracyrtida, Haeckel, 1881, Prodromus, p. 437, 438.

Definition.—Cyrtoidea polythalamia, with annulated shell, divided by three to six or more transverse, horizontal constrictions, into four to seven or more annular joints. (The first joint represents the cephalis, the second the thorax, the third the abdomen, all the following joints together a post-abdomen.)

Synopsis of the three Families and six Subfamilies of Stichocyrtida.

Family LXVIII. Podocampida.

Three radial apophyses.

Mouth open,Stichopilida.
Mouth closed,Stichoperida.

Family LXIX. Phormocampida.

Numerous radial apophyses.

Mouth open,Stichophormida.
Mouth closed,Stichophænida.

Family LXX. Lithocampida.

No radial apophyses.

Mouth open,Stichocorida.
Mouth closed,Stichocapsida.

Family LXVIII. Podocampida.

Three radial apophyses.

Mouth open,
Stichopilida.
Mouth closed,
Stichoperida.

Family LXIX. Phormocampida.

Numerous radial apophyses.

Mouth open,
Stichophormida.
Mouth closed,
Stichophænida.

Family LXX. Lithocampida.

No radial apophyses.

Mouth open,
Stichocorida.
Mouth closed,
Stichocapsida.

Family LXVIII. Podocampida, n. fam.

Artopilida et Artoperida, Stichopilida et Stichoperida, Haeckel, 1881, Prodromus, p. 437-439.

Definition.—Stichocyrtida triradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, and bearing three radial apophyses).

The family Podocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears three external radial apophyses. It may be divided into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichopilida (and the united Artopilida), closed by a lattice-plate in the Stichoperida (and the united Artoperida). The phylogenetic origin of the Podocampida may be found in the Podocyrtida (p. [1314]).

Very few forms only of the Podocampida were hitherto known, viz., Stichopilium (Pterocodon) davisianum, and three fossil species from Barbados, figured by Ehrenberg; Artopera loxia (united by him with Lithornithium), and two species of Pteropilium (sphinx and bombus, both united by him with the three-jointed Pterocanium). In general, the triradiate Stichocyrtida are much rarer and much poorer in specific forms than the triradiate Tricyrtida, their ancestors. We have observed altogether only forty-four species, thirty Stichopilida, and fourteen Stichoperida; the former are disposed among seven, the latter among three genera.

The three radial apophyses appear either as lateral ribs or prominent wings in the thorax (Pl. [77], fig. 8-12), or as three terminal feet around the mouth (Pl. [97], fig. 15). Sometimes the ribs are replaced by three radial combs, or rows of spines, and these may be united by three divergent beams, forming three vaulted bridges with numerous bows (Pl. [75], figs. 10, 11). The lateral wings or ribs, as well as the terminal feet, are either solid or fenestrated.

Synopsis of the Genera of Podocampida.

I. Subfamily Stichopilida.

Mouth of the terminal joint a simple wide opening.

Three lateral appendices or wings (no terminal feet).Lateral wings are solid spines.Cephalis with horn,626. Stichopilium.
Lateral wings are latticed.With horn,627. Artopilium.
Without horn,628. Pteropilium.
Three terminal appendices or feet at the peristome (all with cephalic horn).Three lateral ribs or crests prolonged into the three terminal feet.Feet solid,629. Stichocampe.
Feet latticed,630. Stichopterium.
No lateral ribs. Three terminal feet free.Feet solid,631. Podocampe.
Feet latticed,632. Stichopodium.

II. Subfamily Stichoperida.

Mouth of the terminal joint closed by a lattice-plate.

Last joint rounded, without a vertical basal spine (cephalis with horn).Three lateral solid ribs (or rows of spines),633. Stichopera.
Three lateral latticed wings (or rows of wings),634. Cyrtopera.
Last joint conical, pointed, with a vertical basal spine.Three lateral solid ribs (cephalis with an apical horn),635. Artopera.

I. Subfamily Stichopilida.

Mouth of the terminal joint a simple wide opening.

Three lateral appendices or wings (no terminal feet).
Lateral wings are solid spines.
Cephalis with horn,
626. Stichopilium.
Lateral wings are latticed.
With horn,
627. Artopilium.
Without horn,
628. Pteropilium.
Three terminal appendices or feet at the peristome (all with cephalic horn).
Three lateral ribs or crests prolonged into the three terminal feet.
Feet solid,
629. Stichocampe.
Feet latticed,
630. Stichopterium.
No lateral ribs. Three terminal feet free.
Feet solid,
631. Podocampe.
Feet latticed,
632. Stichopodium.

II. Subfamily Stichoperida.

Mouth of the terminal joint closed by a lattice-plate.

Last joint rounded, without a vertical basal spine (cephalis with horn).
Three lateral solid ribs (or rows of spines),
633. Stichopera.
Three lateral latticed wings (or rows of wings),
634. Cyrtopera.
Last joint conical, pointed, with a vertical basal spine.
Three lateral solid ribs (cephalis with an apical horn),
635. Artopera.

Subfamily 1. Stichopilida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Podocampida with the terminal mouth of the shell open (vel Stichocyrtida triradiata aperta).

Genus 626. Stichopilium,[[243]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three solid lateral ribs or wings, without terminal feet. Cephalis with a horn.

The genus Stichopilium is the most primitive among all Stichocyrtida, and represents perhaps the common ancestral form of this family. The shell is composed of four or more joints (sometimes ten to twelve), has a wide open terminal mouth, and three lateral solid wings or ribs (sometimes a little latticed on the base). Stichopilium may be derived from Theopilium or Pterocorys by addition of new terminal joints.

Subgenus 1. Triacartus, Haeckel, 1881, Prodromus, p. 437.

Definition.—Shell with three annular strictures, and four distinct joints.

1. Stichopilium cortina, n. sp.

Shell ovate, with three sharp strictures. Length of the four joints = 2 : 6 : 3 : 4. Cephalis subspherical, with a slender pyramidal horn of twice the length. The three edges of the horn are prolonged into three strong divergent ribs, along the three first joints, and into three free conical lateral spines, directed downwards, on the end of the third joint. The fourth joint is subcylindrical; its circular, terminal mouth half as broad as the third joint, which is the broadest. Pores small, regular, hexagonal, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.08. Length of the single joints, a 0.02, b 0.06, c 0.03, d 0.04.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Stichopilium costatum, n. sp.

Shell conical, or nearly pyramidal, with three distinct strictures. Length of the four joints = 3 : 5 : 8 : 4. Cephalis subconical, with a stout pyramidal horn of the same length. Thorax campanulate, with six longitudinal ribs, from three of which in the middle arise three horizontal, conical, free spines or wings, about as long as the cephalis. The third large prismatic joint bears twelve parallel ribs, six new ribs being intercalated between the six former. Fourth joint short, cylindrical, without ribs, the wide open mouth not constricted, nearly as broad as the third joint, which is the broadest. Pores small, irregular, polygonal, or roundish.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.12. Length of the single joints, a 0.03, b 0.05, c 0.08, d 0.04.

Habitat.—North Pacific, Station 244 (off Japan), depth 2900 fathoms.

3. Stichopilium bicorne, n. sp. (Pl. [77], fig. 9).

Shell conical, with three slight strictures. Length of the four joints = 4 : 14 : 5 : 3. Cephalis large, conical, with two stout pyramidal, divergent horns of twice the length. From its base (in the middle of the collar stricture) arise three internal, downwardly divergent ribs, which are prolonged on the outside of the upper half of the thorax into three stout, pyramidal, lateral spines (similar to the horns). The fourth joint, with wide open mouth, was the broadest, but not fully developed in the single specimen observed. Pores subregular, hexagonal, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.02, breadth 0.09. Length of the single joints, a 0.02, b 0.07, c 0.025, d 0.015.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Stichopilium davisianum, Haeckel.

Pterocodon davisianus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 298, Taf. ii. fig. 10.

Cycladophora davisiana, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. ii. fig. 11.

Eucyrtidium davisianum, Haeckel, 1862, Monogr. d. Radiol., p. 328.

Pterocanium davisianum, Haeckel, 1862, Monogr. d. Radiol., p. 332.

Shell campanulate, conical, with three slight strictures. Length of the four joints = 2 : 3 : 4 : 3. Cephalis hemispherical, with few small pores and a short conical horn. Thorax campanulate, with larger circular pores, and three recurved, divergent, lateral wings of the same length. Third and fourth joints each with three transverse rows of very large hexagonal pores. The similar form described by Ehrenberg as Cycladophora davisiana, is either a mutilated specimen, or belongs to Lithostrobus.

Dimensions.—Length of the shell (with four joints) 0.12, breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.03.

Habitat.—North Atlantic, Greenland, depth 1000 to 1500 fathoms.

5. Stichopilium campanulatum, n. sp. (Pl. [77], fig. 11).

Shell campanulate, with three slight strictures. Length of the four joints = 3 : 5 : 5 : 4. Cephalis subovate, with an internal rod-cross, and a stout pyramidal horn of the same length. From the middle of the collar stricture arise three divergent collar beams, which descend in the upper half of the campanulate thorax as three divergent ribs, and are prolonged into three free horizontal spines. (In the specimen figured these three wings are very short; in another specimen, found afterwards, there were three solid, pyramidal, horizontal spines, as long as the cephalic horn.) The third joint is the broadest, of about the same length as the fourth. (The annular septum between the two latter is by a mistake not figured). Pores subregular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.17, breadth 0.12. Length of the single joints, a 0.03, b 0.05, c 0.05, d 0.04.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Stichopilium triserratum, n. sp.

Shell slenderly campanulate, with three deep strictures. Length of the four joints = 2 : 4 : 6 : 3. Cephalis hemispherical, with a stout pyramidal horn three times the length. The three edges of the horn are prolonged into three strong prominent ribs along the three first joints; each rib bears a series of stout, irregular, triangular teeth. The fourth joint is without ribs; its constricted mouth is half as broad as the third (broadest) joint. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.08. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.03.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Stichopilidium, Haeckel.

Definition.—Shell with four or more annular strictures and five or more joints.

7. Stichopilium macropterum, Haeckel.

Rhopalocanium varietas, Bury, 1862, Polycystins of Barbados, pl. xvii. fig. 7.

Shell slenderly conical, with five deep strictures. Length of the six joints = 2 : 5 : 4 : 3 : 3 : 6. Cephalis hemispherical, with a stout conical horn of twice the length. Thorax campanulate, with three large, triangular, widely divergent wings or ribbed solid spines, nearly as long as the shell. The breadth of the joints increases gradually; the last joint is the broadest, with wide open mouth. Pores subregular, circular.

Dimensions.—Length of the shell (with six joints) 0.23, breadth 0.1. Length of the single joints, a 0.02, b 0.05, c 0.04, d 0.03, e 0.03, f 0.06.

Habitat.—Fossil in Barbados.

8. Stichopilium pectinatum, n. sp.

Shell slenderly conical, with nine sharp strictures. All ten joints have nearly equal length, and increase gradually in breadth; the last joint is the broadest, and twice as long as each of the others, with wide open mouth. Cephalis subspherical, with a conical horn of the same length. Each joint (excepting the first and the last) bears three lateral, nearly horizontal spines, and the bases of all the spines are connected by three longitudinal, divergent ribs. Pores subregular, hexagonal. (Similar to Stichopera pectinata, Pl. [75], fig. 11.)

Dimensions.—Length of the shell (with ten joints) 0.32, breadth 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

9. Stichopilium thoracopterum, n. sp.

Shell slenderly ovate, twice as long as broad, with eleven slight annular strictures. The twelve joints (excepting the second) are of nearly equal length, or alternately longer and shorter. The eighth joint is the broadest, one and a half times as broad as the slightly constricted mouth. Cephalis small, hemispherical, with a pyramidal horn of twice the length. Thorax (or second joint) campanulate, twice to three times as long as each of the eleven other joints, with three longitudinal ribs, prolonged into three divergent, slender, free spines. Pores small, regular, hexagonal.

Dimensions.—Length of the shell (with twelve joints) 0.22, breadth 0.11. Length of each joint (on an average) 0.015 to 0.017, thorax 0.035.

Habitat.—South Pacific, Station 296, depth 1825 fathoms.

Genus 627. Artopilium,[[244]] Haeckel, 1881, Prodromus, p. 437.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three latticed lateral ribs or wings, without terminal feet. Cephalis with a horn.

The genus Artopilium (including also the genera Trictenartus, Pterocorythium, Stichopterygium, and Clathropyrgus of my Prodromus) has a shell of the same form as the preceding Stichopilium, but it differs in the fenestration of the three lateral ribs or wings, which in the latter are solid. The limit between the two genera is often not sharp. Artopilium may be also derived from the three-jointed Dictyoceras by addition of new terminal joints.

Subgenus 1. Trictenartus, Haeckel, 1881, Prodromus, p. 437.

Definition.—Shell with three annular strictures and four joints.

1. Artopilium elegans, n. sp. (Pl. [75], fig. 1).

Shell three-sided pyramidal, with three annular strictures. Length of the four joints = 1 : 2 : 9 : 3. Cephalis small, hemispherical, with two large, prismatic, divergent horns of three times the length. The three prominent edges of the second and third joints are finely latticed and dentated, and at the basal end of the third joint are prolonged into three stout, free, pointed, pyramidal, divergent wings, about as long as the horns. The fourth joint is only as long as the second, three-sided prismatic, its wide triangular mouth is armed with six parallel, vertical, slender teeth (two between every three wings). Network very delicate and regular, in the first and second joints with circular, in the third and fourth joints with small hexagonal meshes.

Dimensions.—Length of the shell (with four joints) 0.3, breadth of the third joint 0.3, of the fourth 0.2. Length of the single joints, a 0.02, b 0.04, c 0.18, d 0.06.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Artopilium longicorne, n. sp. (Pl. [77], fig. 10).

Shell subovate, with three internal annular septa. Length of the four joints = 2 : 3 : 2 : 6. Cephalis hemispherical, with a very large three-sided prismatic horn, nearly as long as the shell. Along the three following joints arise three broad, triangular, latticed wings, about as long as the shell. The fourth joint is the broadest, and twice as broad as the constricted mouth. Pores in the two upper joints regular, circular, in the two lower and the three wings hexagonal.

Dimensions.—Length of the shell (with four joints) 0.13, breadth 0.09. Length of the single joints, a 0.02, b 0.03, c 0.02, d 0.06.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

3. Artopilium cyrtopterum, n. sp. (Pl. [77], fig. 12).

Shell subovate, with three sharp strictures. Length of the four joints = 1 : 2 : 3 : 3. Cephalis subspherical, with a stout, pyramidal horn of twice the length. Along the second and third joints arise three broad, triangular, latticed wings, about half as long as the shell. The third joint is the broadest, and twice as broad as the constricted mouth. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.1. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Clathropyrgus, Haeckel, 1881, Prodromus, p. 439.

Definition.—Shell with four or more annular strictures, and five or more joints.

4. Artopilium trifenestra, n. sp. (Pl. [75], fig. 7).

Clathropyrgus trifenestra, Haeckel, 1881, Prodromus et Atlas (loc. cit.).

Shell tower-shaped, nearly cylindrical, with nine deep strictures. The ten joints are of different lengths and breadths. The third and fourth joints are the longest, twice as long as the first, fifth, sixth, eighth, and ninth joints. The third, seventh, and tenth joints are the broadest, and nearly twice as broad as the second and ninth joints. The mouth of the last joint is dilated. The second joint bears three divergent ribs, and the third joint (as prolongations of these) three broad, triangular, lattice-wings, and between the latter three large, ovate openings or windows, recalling those in Clathrocanium (Pl. [64]). Cephalis subspherical, with a pyramidal horn of twice the length. Pores subregular, circular, hexagonally framed.

Dimensions.—Length of the shell (with ten joints) 0.28, of the first and ninth joints 0.02, of the third and fourth joints 0.04; breadth of the third and seventh joints 0.08, of the second and ninth joints 0.04.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

5. Artopilium trigonopterum, n. sp.

Shell in the upper half campanulate-conical, in the lower half cylindrical, with seven internal septa. The four middle joints are equal in length, each about twice as long as each of the two first and of the two last joints. Cephalis hemispherical, with a conical horn of the same length. Along the first three joints arise three broad, triangular, lattice-wings. Pores small, regular, hexagonal, in the wings and the two first joints circular. The five lower joints are of equal breadth.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1. Length of the four middle joints, each about 0.034, of the two first and the two last, each 0.017.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

6. Artopilium cornutella, n. sp.

Shell slenderly conical, without external strictures, but with twelve to fifteen internal annular septa. All thirteen to sixteen joints are nearly equal or slightly different in length, but increase gradually in breadth. Along the whole shell arise three narrow, divergent lattice-wings, increasing in height towards the wide open mouth. Pores subregular, square, in three to four transverse rows on each joint, half as large in the three wings as in the joints. Cephalis small, subspherical, with a conical horn of twice the length. (In the specimen described the axis of the slender cone was straight, in another incomplete specimen curved; this may perhaps be a separate species, Artopilium curvatum.)

Dimensions.—Length of the shell (with sixteen joints) 0.3, basal breadth 0.12. Length of each single joint (on an average), 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

7. Artopilium stichopterygium, n. sp. (Pl. [75], fig. 8).

Stichopterygium tanypterum, Haeckel, 1881, Prodromus, p. 439, et Atlas.

Shell slenderly ovate, subconical, with five deep strictures. The four lower joints are nearly equal in length, each about twice as long as each of the first two joints. The fourth and fifth joints are the broadest. Along the whole shell arise three broad, triangular wings, which envelop the long, slender, pyramidal horn of the cephalis. In the delicate and loose lattice-work of each wing is a longitudinal series of six large, ovate apertures, one on each joint. The small pores of the shell are irregular, polygonal, or roundish.

Dimensions.—Length of the shell (with six joints) 0.17, breadth 0.08. Length of each of the four lower joints 0.03, of each of the two upper joints 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

8. Artopilium anomalum, Haeckel.

Eucyrtidium anomalum, Haeckel, 1862, Monogr. d. Radiol., p. 323, Taf. vii. figs. 11-13.

Lithocampe anomala, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 839.

Stichopterygium anomalum, Haeckel, 1881, Prodromus, p. 439.

Shell five-jointed, with four internal septa, of a peculiar, irregular, and abnormal form. Cephalis small, hemispherical, with an oblique, curved horn. Thorax inflated, campanulate, with three large, latticed, and carinated protuberances. The third joint (the first abdominal joint) nearly as large as the thorax, two to three times as long as the two last joints, the septa of which are connected in a peculiar manner by a common nodal point on one side. Pores subregular, circular. (Compare the detailed description of this remarkable species—perhaps the type of a peculiar genus, Stichopterygium—in my Monograph, loc. cit.)

Dimensions.—Length of the shell (with five joints) 0.15, breadth 0.1.

Habitat.—Mediterranean (Messina), surface.

Genus 628. Pteropilium,[[245]] n. gen.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three latticed external ribs or wings, without terminal feet. No horn upon the cephalis.

The genus Pteropilium (confounded by Ehrenberg with Pterocanium) differs from this three-jointed form by addition of new terminal joints. The shell-form is in general the same as in the preceding species, from which it may be derived by phylogenetic loss of the cephalic horn.

1. Pteropilium sphinx, Haeckel.

Pterocanium sphinx, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 255, Taf. xvii. fig. 5.

Shell slenderly conical, with three slight strictures. Each of the two last joints as long as the two first joints together. Cephalis hemispherical. Third joint with three prominent, divergent ribs, which are prolonged along the fourth joint into three latticed, triangular wings, ending in a free, strong, conical spine. Pores subregular, circular, twice as broad in the fourth joint as in the third, and three times as broad as in the second joint.

Dimensions.—Length of the shell (with four joints) 0.15, of the single joints, a 0.02, b 0.03, c 0.05, d 0.05; breadth of the third joint 0.09, of the fourth joint 0.06.

Habitat.—Fossil in Barbados.

2. Pteropilium bombus, Haeckel.

Pterocanium bombus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 4.

Shell broadly conical, with three deep strictures. Length and breadth of the four joints, gradually increasing giving the proportion 2 : 4 : 5 : 6. Cephalis hemispherical, second joint with three prominent ribs, which are prolonged along the third and fourth joints into three slender, triangular pointed wings, with few pores at the base. Pores of the shell subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.17, of the single joints, a 0.02, b 0.04, c 0.05, d 0.06; basal breadth 0.11.

Habitat.—Fossil in Barbados.

3. Pteropilium pyramis, n. sp.

Shell three-sided, pyramidal, with five deep strictures. Length and breadth of the six joints gradually increasing towards the wide mouth. Cephalis subconical. Along the four first joints arise three slender, divergent ribs, which at the fifth joint become three free, triangular, latticed wings, with long, descending, terminal spines. The sixth joint is free, without wings. Pores irregular, roundish.

Dimensions.—Length of the shell (with six joints) 0.2, basal breadth 0.2.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 629. Stichocampe,[[246]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three solid lateral ribs or wings, which are prolonged into three solid terminal feet. Cephalis with a horn.

The genus Stichocampe, together with the three following genera, represent a peculiar small group among the Stichocyrtida, differing from all other members of this family in the possession of three free terminal feet around the open mouth. In the two genera, Stichocampe and Stichopterium, these three feet are the terminal prolongations of three lateral ribs or crests, while in the two genera developed later, Podocampe and Stichopodium, the three original ribs are lost, and only the three free feet remain. Stichocampe (the most primitive of these four genera) may be derived from Theopodium by addition of new joints.

1. Stichocampe divergens, n. sp.

Shell spiny, broadly pyramidal, with six deep strictures. Seven joints gradually increasing in breadth and length, the seventh twice as broad as the fourth. Pores subregular, circular, hexagonally framed. The prominent edges of the pyramis are prolonged over the wide mouth into three slender, straight, divergent feet, half as long as the shell.

Dimensions.—Length of the shell (with seven joints) 0.3, of the last joint 0.06, of the fourth 0.03; breadth 0.25.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Stichocampe convergens, n. sp.

Shell smooth, slenderly pyramidal, with eight distinct strictures. All nine joints nearly equal in length. Pores regular, circular, forming three or four transverse rows in each joint. The smooth edges of the pyramis are prolonged over the wide mouth into three slender, slightly curved, and convergent feet, twice as long as one joint.

Dimensions.—Length of the shell (with nine joints) 0.25, of each joint, about 0.035; breadth 0.11.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

Genus 630. Stichopterium,[[247]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta), with three lateral ribs or wings, which are prolonged into three latticed, terminal feet. Cephalis with a horn.

The genus Stichopterium has in general the same shell-formation as the nearly allied Stichocampe, but differs from this ancestral form in the fenestration of the three terminal feet. It corresponds, therefore, to Pterocanium among the Tricyrtida.

1. Stichopterium pterocanium, n. sp.

Shell campanulate, with three distinct strictures. Length of the four joints = 2 : 3 : 4 : 3. Cephalis subspherical, with a conical horn of twice the length. Pores regular, hexagonal, with thin bars. From the collar stricture arise three divergent ribs, which in the fourth joint become latticed and prolonged over its mouth into three slender, pyramidal, latticed, divergent feet, nearly as long as the shell. (Similar to Pterocanium bicorne, Pl. [73], fig. 5, but with four distinct strictures.)

Dimensions.—Length of the shell (with four joints) 0.12, breadth 0.1. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.03.

Habitat.—South Pacific (off Patagonia), Station 304, surface.

2. Stichopterium virgineum, n. sp.

Shell three-sided, pyramidal, with four sharp strictures. Length of the five joints = 1 : 4 : 3 : 2 : 1. Cephalis hemispherical, with a pyramidal horn three times the length. Pores subregular, circular, in the second campanulate joint twice or three times as broad as in the four other joints. From the base of the cephalic horn arise three divergent ribs, which descend over the whole shell, and in the fourth joint become latticed and prolonged over the wide mouth of the fifth joint into three latticed, pyramidal feet, as long as the second joint. (Similar in general form to Pterocanium virgineum, Pl. [73], fig. 6.)

Dimensions.—Length of the shell (with five joints) 0.22, breadth 0.16. Length of the single joints, a 0.02, b 0.08, c 0.06, d 0.04, e 0.02.

Habitat.—Central Pacific, Station 281, surface.

3. Stichopterium dictyopodium, n. sp.

Shell subovate, with five internal annular septa. The third and the fourth joints are about twice as long as the two first and the two last joints. The fifth joint is the broadest. Pores small and numerous, regular, circular. The three first joints are without ribs. From the third stricture arise three divergent, triangular, latticed wings, which descend along the three last joints, and are prolonged over the wide mouth as three slender, fenestrated, divergent feet, two-thirds as long as the shell.

Dimensions.—Length of the shell (with six joints) 0.18, breadth 0.12. Length of the two middle joints 0.04, of the four others 0.02 to 0.03.

Habitat.—South Pacific, Station 288, surface.

Genus 631. Podocampe,[[248]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta), without lateral ribs or wings, but with three free, solid, terminal feet. Cephalis with a horn.

The genus Podocampe is next allied to Stichocampe, and has also three solid, free feet around the mouth, but it has lost the three lateral ribs of the latter. It corresponds to Podocyrtis among the Tricyrtida, and may be derived from this by addition of new terminal joints.

1. Podocampe tripodiscus, n. sp.

Shell ovate, with three annular septa. The fourth joint is the broadest, and as long as the three other joints together. Cephalis hemispherical, with a pyramidal horn of twice the length. Mouth constricted, with three convergent, curved, triangular feet, half as long as the last joint. Pores subregular, circular. (Similar to Podocyrtis pedicellaria, Pl. [72], fig. 8, but larger, with more slender feet, and four joints instead of three.)

Dimensions.—Length of the shell (with four joints) 0.2, of the last joint 0.1; breadth 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Podocampe trictenota, n. sp. (Pl. [97], fig. 15).

Shell slenderly ovate, nearly spindle-shaped, with three annular septa. The third joint is the broadest, somewhat longer than the second and third joints, and three times as long as the hemispherical cephalis, which bears a strong pyramidal horn of twice the length. Along the two first joints arise three divergent, dentate crests, each with four to six strong pyramidal teeth. Mouth strongly constricted, only as broad as the cephalis, with three conical, vertical, parallel feet, as long as the cephalis. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.14, of the third joint 0.06, of the last 0.04; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Podocampe conica, n. sp.

Shell conical, with five distinct strictures. Six joints gradually increasing in length and breadth. The sixth joint is the broadest, and twice as long as the fifth joint, three times as long as the fourth. Cephalis conical, with a stout, conical horn of the same length. Mouth little constricted, with three divergent, conical feet, half as long as the shell. Pores subregular, circular. (Similar to Podocyrtis lithoconus, Pl. [72], fig. 3, but with six joints instead of three, and with divergent, slender feet.)

Dimensions.—Length of the shell (with six joints) 0.18, of the last joint 0.06; breadth 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Podocampe cornuta, n. sp.

Shell slenderly conical, with seven distinct strictures. Eight joints of nearly equal length, gradually increasing in breadth. Along the three last joints arise three prominent crests, which are prolonged over the wide mouth into three divergent, conical feet, half as long as the shell. Cephalis hemispherical, with a conical, slender, curved horn, three times the length. Pores subregular, hexagonal.

Dimensions.—Length of the shell (with eight joints) 0.16, of each single joint (on an average) 0.02; basal breadth 0.07.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 632. Stichopodium,[[249]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) without lateral ribs or wings, but with three free latticed terminal feet. Cephalis with a horn.

The genus Stichopodium differs from the preceding genus Podocampe in the fenestration of the three free terminal feet. It agrees in this character with the genus Stichopterium, and may be derived either from this by loss of the lateral ribs, or from the three-jointed Pterocanium by addition of new shell-joints.

1. Stichopodium dictyopodium, n. sp. (Pl. [75], fig. 6).

Shell subcylindrical, in the upper third conical, with six or seven internal annular septa. All seven or eight joints are about equal in length, except the small hemispherical cephalis, which is scarcely half as long, and bears an oblique, conical horn of the same length. Pores small and numerous, regular, circular, quincuncial. The last joint with wide open mouth, and a peristome of three large, triangular, latticed, shovel-shaped, vertical feet.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.11. Length of each single joint about 0.03, of the feet 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subfamily 2. Stichoperida, Haeckel, Prodromus, p. 439.

Definition.—Podocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida triradiata clausa).

Genus 633. Stichopera,[[250]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichoperida (vel Stichocyrtida triradiata clausa) with three solid lateral ribs, or three longitudinal combs of spines. Cephalis with a horn.

The genus Stichopera, and the two following genera, represent the small subfamily of Stichoperida, or those triradiate Stichocyrtida in which the terminal mouth is closed by lattice-work. In Stichopera the three radial appendages are either solid lateral ribs or longitudinal combs of spines; the closed basal part of the shell is rounded, not pointed. It may be derived either from Stichopilium by closure of the mouth, or from Lithornithium by increase of the number of the joints.

Subgenus 1. Stichoperina, Haeckel.

Definition.—Shell with three solid radial ribs, or longitudinal dentate crests.

1. Stichopera ovata, n. sp.

Shell ovate, with three distinct strictures. Length of the four joints = 2 : 3 : 4 : 6. The fourth joint is the broadest, and twice as long as the second, with hemispherical basal pole. Cephalis hemispherical, with a conical horn of twice the length. Along the second and third joints descend three prominent divergent ribs, which disappear in the middle zone of the fourth joint. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.1. Length of the single joint, a 0.02, b 0.03, c 0.04, d 0.06.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Stichopera lagena, n. sp.

Shell bottle-shaped, with six sharp strictures; the upper half is slender, conical, and composed of six joints of nearly equal length, the lower half is formed only by the last subspherical joint. Cephalis subspherical, with a pyramidal horn of the same length. From its base arise three divergent ribs, which attain the greatest height in the fourth joint, and disappear in the sixth joint. (Similar to Stichophæna ritteriana, Pl. [75], fig. 12, but only with three ribs and seven joints.) Pores regular, hexagonal.

Dimensions.—Length of the shell (with seven joints) 0.25. Length of each joint 0.02 to 0.025, of the last joint 0.12; breadth 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Stichopera serrata, n. sp.

Shell bottle-shaped, with eight deep strictures. The first eight joints are little different in length, and form together a slender cone, while the last joint is four times as long (half as long as this cone), and subspherical. Cephalis conical, with a slender, prismatic horn of three times the length. Along the whole shell arise three divergent, serrate ribs, which disappear towards the hemispherical, basal pole. Pores subregular, hexagonal.

Dimensions.—Length of the shell (with nine joints) 0.21, breadth 0.08; length of each joint 0.016 to 0.019, of the last joint 0.07.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

Subgenus 2. Sticholagena, Haeckel.

Definition.—Shell with three radial combs or longitudinal rows of isolated spines (instead of the three radial ribs).

4. Stichopera pectinata, n. sp. (Pl. [75], fig. 11).

Shell club-shaped, with nine sharp strictures. The nine upper joints increase gradually in length and breadth, and are together three times as long as the inflated, inversely campanulate and rounded last joint. Each joint (excepting the first and the last) bears three thin, bristle-shaped spines, which are directed obliquely upwards. Cephalis subspherical, with a slender, conical horn of twice the length. Pores subregular, in the upper half circular, in the lower hexagonal.

Dimensions.—Length of the shell (with ten joints) 0.22, breadth 0.09; length of the eighth and ninth joints 0.02, of the last joint 0.075.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Stichopera clavata, n. sp.

Shell club-shaped, with eight sharp strictures, very similar in form and structure to that of the preceding species, but differing from it in the club-like form of the inflated last joint, which is nearly half as long as the shell; its lower half is broader than the upper (the reverse being the case in the preceding species). The lateral spines of the three combs are not directed upwards, but downwards. Cephalis with a curved, conical horn of the same length.

Dimensions.—Length of the shell (with nine joints) 0.2, breadth 0.08; length of the eighth joint 0.02, of the last joint 0.09.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

6. Stichopera verticillata, n. sp.

Shell club-shaped, with ten sharp strictures, similar in form and structure to that of the two preceding species, but differing from them in the ovate form of the slender last joint, which is one-third as long as the whole shell, and five times as long as the preceding joint. The lateral spines of the three combs are directed nearly horizontally, and are much more numerous, each joint (excepting the first and last) bears six to twelve spines (two, three, or four in each radius). They form together about thirty horizontal verticils, each with three spines. Cephalis with a curved, conical horn of three times the length.

Dimensions.—Length of the shell (with eleven joints) 0.28, breadth 0.09; length of the tenth joint 0.02, of the last joint 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 634. Cyrtopera,[[251]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichoperida (vel Stichocyrtida triradiata clausa) with three latticed lateral wings, or three longitudinal rows of lattice wings. Cephalis with a horn.

The genus Cyrtopera differs from the preceding Stichopera in the fenestration of the three lateral wings, and bears therefore to it the same relation that Sethornithium exhibits to Lithornithium among the Tricyrtida.

Subgenus 1. Artopera, Haeckel, 1881, Prodromus, p. 438.

Definition.—Shell with three annular strictures and four joints.

1. Cyrtopera thoracoptera, n. sp. (Pl. [75], fig. 3).

Artopera thoracoptera, Haeckel, 1881, Prodromus et Atlas (loc. cit.).

Shell inflated, with three very deep strictures. Length of the four joints = 2 : 7 : 8 : 6. Cephalis hemispherical, with a slender, prismatic horn, half as long as the shell. Thorax subspherical, in its middle third with three latticed, triangular wings of half the length. Abdomen with inflated third, and inversely hemispherical fourth joint; the third is the broadest. Pores subregular, hexagonal, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.23. Breadth of the third (broadest) joint 0.13. Length of the single joints, a 0.02, b 0.07, c 0.08, d 0.06.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Cyrtopera ornithoptera, n. sp.

Shell broadly ovate, with three slight strictures. Length of the four joints = 1 : 2 : 3 : 4. Cephalis hemispherical, with a slender, pyramidal horn of three times the length. Along the second and third joints arise with broad base three latticed, triangular wings, nearly as long as the whole shell. Abdomen inflated. The fourth joint is the broadest and longest, with hemispherical basal pole. Pores subregular, hexagonal. (Similar to Artopilium longicorne, Pl. [77], fig. 10, but with more closely reticulated network, and perfectly closed mouth.)

Dimensions.—Length of the shell (with four joints) 0.2. Breadth of the fourth (broadest) joint 0.14. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.08.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Cyrtopera gasteroptera, n. sp.

Shell slenderly ovate, with three distinct strictures. Length of the four joints = 2 : 6 : 7 : 6. Cephalis subspherical, with a stout pyramidal horn of the same length. The three following joints have nearly equal length; the third is the broadest. The thorax exhibits three divergent solid ribs; as prolongations of these, three descending latticed wings, of about the same length, arise from the third joint, with broad triangular base. The fourth joint is inversely conical, blunt. Pores irregular, roundish. (Similar to Hexalatractus fusiformis, Pl. [68], fig. 13, but with three wings and four joints.)

Dimensions.—Length of the shell (with four joints) 0.21. Breadth of the third (broadest) joint 0.11. Length of the single joints, a 0.02, b 0.06, c 0.07, d 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Cyrtolagena, Haeckel, 1879, Atlas (Pl. [75]).

Definition.—Shell with four or more annular strictures, and five or more joints.

4. Cyrtopera laguncula, n. sp. (Pl. [75], fig. 10).

Cyrtolagena laguncula, Haeckel, 1879, Manuscript et Atlas (loc. cit.).

Shell bottle-shaped, with seven sharp strictures; the upper part is slender, conical, composed of seven joints of nearly equal length; the lower part is only formed by the spherical last joint. Cephalis subspherical, with a slender curved horn at three times the length. Along the whole shell arise three longitudinal combs or rows of ascending spines (three on each joint, fifteen on the last). These are connected by three divergent longitudinal rods, so that three elegant fenestrated ribs are formed (each rib with one series of large square meshes). Pores in the seven upper joints regular, circular, in the last polygonal, irregular and larger.

Dimensions.—Length of the shell (with eight joints) 0.17, of the last joint 0.08; breadth 0.08.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

5. Cyrtopera lagenella, n. sp.

Shell bottle-shaped, with twelve sharp strictures, very similar in form and structure to the preceding species; but instead of the three simple fenestrated ribs there arise here, along the shell, three series of short, triangular, latticed wings. The four first and the last joints are without wings. The hemispherical cephalis bears a curved conical horn, as long as the subspherical last joint. The twelve joints of the upper conical part are nearly equal in length, with regular, small, hexagonal pores. The last inflated joint is one-third as long as the shell, and has larger, irregular, polygonal pores.

Dimensions.—Length of the shell (with thirteen joints) 0.25, of the last joint 0.08; breadth 0.1.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Genus 635. Artopera,[[252]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichoperida with three solid lateral ribs or wings, and with a vertical basal spine on the end of the pointed last joint. Cephalis with a horn.

The genus Artopera differs from its ancestral genus, Stichopera, in the development of a vertical terminal spine on the end of the last joint, and bears therefore to it the same relation that Rhopalatractus exhibits to Rhopalocanium among the Tricyrtida.

1. Artopera loxia, Haeckel.

Lithornithium loxia, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 8; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 78, Taf. iv. fig. 8.

Shell spindle-shaped, with three deep strictures. Length of the four joints = 2 : 5 : 5 : 4. Cephalis subspherical, hyaline, without pores, with a thick conical horn of the same length. From the two following joints, which are nearly equal in size and of campanulate form, arise, with broad base, three divergent, slender, triangular wings. The fourth joint is smaller, inversely conical, and bears on the basal pole a strong, three-sided pyramidal, vertical spine, half as long as the shell. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.07. Length of the single joints, a 0.02, b 0.055, c 0.055, d 0.05.

Habitat.—Fossil in Barbados.

2. Artopera motacilla, n. sp.

Shell spindle-shaped, with three distinct strictures. Length of the four joints = 1 : 2 : 3 : 2. Cephalis subspherical, with a conical horn of twice the length. From the second joint arise three longitudinal, smooth, divergent ribs, which are prolonged over the third joint, and terminate at the third stricture in three short, conical teeth. The fourth is inversely conical, and bears on the basal pole a strong, vertical, cylindrical spine, nearly half as long as the shell. Pores subregular, circular, hexagonally framed. (Similar to Rhopalatractus pentacanthus, Pl. [68], fig. 11, but differing in the presence of three sharp strictures, and a large, conical, basal joint).

Dimensions.—Length of the shell (with four joints) 0.18. Breadth of third (broadest) joint 0.09. Length of the single joint, a 0.02, b 0.04, c 0.06, d 0.04.

Habitat.—Western Tropical Pacific (Philippine Sea), Station 198, depth 2150 fathoms.

3. Artopera fusiformis, n. sp.

Shell spindle-shaped, with three distinct strictures. Length of the four joints = 2 : 3 : 5 : 5. Cephalis conical, with a strong, conical horn of the same length. Along the three first joints arise three divergent, irregularly dentate ribs, which at the second joint bear stronger, pyramidal teeth, also at the third stricture a strong, terminal tooth. Fourth joint without ribs, inversely conical, with a strong, conical, terminal spine of half the length on the basal pole. Pores subregular, circular, double-edged.

Dimensions.—Length of the shell (with four joints) 0.15. Breadth of the third (broadest) joint 0.08. Length of the single joint, a 0.02, b 0.03, c 0.05, d 0.05.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Family LXIX. Phormocampida, n. fam.

Artophormida et Artophænida, Stichophormida et Stichophænida, Haeckel, 1881, Prodromus, pp. 438, 439.

Definition.—Stichocyrtida multiradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, with numerous, four to nine or more, radial apophyses.)

The family Phormocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears numerous (four to eight or more) radial apophyses. We divide it into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichophormida (and the united Artophormida), closed by a lattice-plate in the Stichophænida (and the united Artophænida). The phylogenetic origin of the Phormocampida may be found in the Phormocyrtida.

Three fossil forms only of Phormocampida were hitherto known, two of which were described by Stöhr as Eucyrtidium acutatum and Lithocampe fimbriata, the third by Ehrenberg as Eucyrtidium barbadense; the latter belongs to Artophormis, the two former to Cyrtophormis. All the other Phormocampida here described, forming together thirty-one species, are new; twenty-two of them belong to the Stichophormida, and nine to the Stichophænida. The latter are disposed in two, the former in four genera.

The number of the radial apophyses is sometimes six or nine, sometimes twelve or more, usually a multiple of three. They are either lateral ribs or wings (Pl. [75], figs. 2, 5, 12), or terminal feet (Pl. [77], figs. 13 to 18). Usually they are solid, not latticed, and not strongly developed. The majority of Phormocampida have probably been derived from Phormocyrtida by growth of the abdomen, which becomes annulated by transverse constrictions. Some forms, however, may be derived from similar Podocampida, by interpolation of three to six or more secondary apophyses between the three primary or perradial apophyses.

Synopsis of the Genera of Phormocampida.

I. Subfamily Stichophormida.

Mouth of the terminal joint open, simple.

Shell conical or pyramidal. Mouth wide open, not constricted.Lateral ribs prolonged into the terminal feet,636. Stichophormis.
No lateral ribs. Feet free, terminal,637. Phormocampe.
Shell ovate or spindle-shaped. Mouth more or less constricted.Lateral ribs prolonged into the terminal feet,638. Artophormis.
No lateral ribs. Feet free, terminal,639. Cyrtophormis.

II. Subfamily Stichophænida.

Mouth of the terminal joint closed by a lattice-plate.

Six radial ribs or wings,640. Artophæna.
Nine radial ribs or wings,641. Stichophæna.

I. Subfamily Stichophormida.

Mouth of the terminal joint open, simple.

Shell conical or pyramidal. Mouth wide open, not constricted.
Lateral ribs prolonged into the terminal feet,
636. Stichophormis.
No lateral ribs. Feet free, terminal,
637. Phormocampe.
Shell ovate or spindle-shaped. Mouth more or less constricted.
Lateral ribs prolonged into the terminal feet,
638. Artophormis.
No lateral ribs. Feet free, terminal,
639. Cyrtophormis.

II. Subfamily Stichophænida.

Mouth of the terminal joint closed by a lattice-plate.

Six radial ribs or wings,
640. Artophæna.
Nine radial ribs or wings,
641. Stichophæna.

Subfamily 1. Stichophormida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Phormocampida with the terminal mouth of the shell open (vel Stichocyrtida multiradiata aperta).

Genus 636. Stichophormis,[[253]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta) with conical or pyramidal shell, bearing in its wall numerous lateral ribs, which are prolonged into terminal feet. Mouth not constricted.

The genus Stichophormis and the three following genera represent together the subfamily of Stichophormida, or of those multiradiate Stichocyrtida in which the mouth remains open; they may be derived therefore either from the Theophormida by increasing the number of the shell-joints, or from the Stichopilida by the interpolation of new radial ribs between the three primary ribs. Stichophormis may have been derived in the former way from Theophormis.

Subgenus 1. Stichophormium, Haeckel.

Definition.—Shell with six prominent longitudinal ribs, which are prolonged into six (sometimes five or seven) divergent free feet over the mouth.

1. Stichophormis pyramidalis, n. sp.

Shell slenderly pyramidal, with three annular septa, and six prominent radial ribs, which arise from the collar-septum, and are prolonged on the mouth into six free, divergent, pyramidal feet, about as long as the shell. Length of the four joints = 2 : 3 : 5 : 8. Cephalis subspherical, with a stout, pyramidal horn of twice the length. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, basal breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.05, d 0.08.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

2. Stichophormis lucerna, n. sp.

Shell slenderly pyramidal, with three annular septa and six prominent radial ribs, which arise from the second stricture, and are prolonged over the mouth into six free, divergent, cylindrical feet, half as long as the shell. Length of the four joints = 1 : 2 : 3 : 15. Cephalis hemispherical, with a prismatic horn of the same length. Pores in the first and second joints very small and scarce, in the third campanulate joint circular, hexagonally framed, in the colossal fourth joint very large, polygonal (each about as large as the third joint).

Dimensions.—Length of the shell (with four joints) 0.4, basal breadth 0.2. Length of the single joints a 0.02, b 0.04, c 0.06, d 0.3.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichophormis cornutella, n. sp. (Pl. [75], fig. 9).

Shell slenderly conical, with nine annular strictures and six longitudinal divergent ribs, which arise in the middle of the shell (from the sixth or seventh stricture), and are prolonged over the wide mouth into six slender bristle-shaped feet, about half as long as the shell. The bases of the feet are connected by arcades of lattice-work. All ten joints have nearly the same length and regular hexagonal pores (in the first and second joints circular). Cephalis hemispherical, with a very large curved horn, nearly half as long as the shell, and on one side decurrent to the fourth or fifth joint.

Dimensions.—Length of the shell (with ten joints) 0.16, of each single joint about 0.016; basal breadth 0.07.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Stichophormiscus, Haeckel.

Definition.—Shell with nine prominent radial ribs, which are prolonged over the mouth into nine (sometimes eight or ten) divergent free feet.

4. Stichophormis novena, n. sp. (Pl. [79], fig. 9).

Shell slenderly conical, very similar to the preceding, but with eleven annular strictures and nine divergent ribs, which arise from the tenth or eleventh stricture, and are prolonged over the wide mouth into nine bristle-shaped feet, half as long as the shell. The length of the twelve joints increases gradually; the tenth is twice as long as the sixth. Pores regular, circular. Cephalis hemispherical, with a curved conical horn of twice the length. (In the somewhat mutilated specimen figured, the horn and the nine feet were broken off, but were well preserved in another specimen, found afterwards.)

Dimensions.—Length of the shell (with twelve joints) 0.22, eighth joint 0.02, fourth joint 0.01; basal breadth 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Stichophormis radiata, n. sp.

Shell slender, conical, with fourteen annular strictures, and nine radial ribs; three primary ribs arise from the third stricture, the other six (secondary) ribs from the ninth stricture; all are prolonged over the mouth into nine slender bristle-shaped feet, about twice as long as one joint. All joints have nearly the same length. Cephalis subspherical, with a straight, conical horn three times the length. Pores regular, hexagonal.

Dimensions.—Length of the shell (with fifteen joints) 0.24, of each joint, about 0.016; basal breadth 0.12.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Genus 637. Phormocampe,[[254]] n. gen.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta), with conical or pyramidal shell, without lateral ribs. Mouth dilated, with a corona of terminal feet.

The genus Phormocampe may be derived from the preceding Stichophormis by loss of the lateral ribs, whilst the terminal feet remain. It bears therefore to the latter the same relation that Calocyclas exhibits to Theophormis among the Tricyrtida.

Subgenus 1. Anthocorys, Haeckel, 1881, Prodromus, p. 437.

Definition.—Shell with three transverse strictures or annular septa, and with four distinct joints.

1. Phormocampe campanula, n. sp. (Pl. [77], fig. 13).

Anthocorys campanula, Haeckel, 1881, Prodromus et Atlas (loc. cit.).

Shell campanulate, with three internal, annular septa. Length of the four joints = 5 : 2 : 8 : 3. Cephalis three-sided, pyramidal, slender, bearing a pyramidal horn of the same length, with three dentate edges. Thorax very small, hemispherical. Third joint very large, campanulate. Fourth joint of the same breadth, but only one-third as long. Pores subregular, circular. Peristome with a coronal of twelve to fifteen conical, divergent feet, as long as the last joint.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.09. Length of the single joints, a 0.05, b 0.02, c 0.08, d 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Phormocampe lamprocyclas, n. sp. (Pl. [77], fig. 16).

Shell conical, with three internal annular septa. Length of the four joints = 1 : 1 : 3 : 4. Cephalis subspherical, as large as the thorax, with a stout, pyramidal horn of three times the length, bearing at the apex a spinulate knob. The fourth joint is the broadest, and has large, circular, hexagonally-framed pores, two to three times as broad as the circular pores of the three first joints. Peristome with a double coronal of short, conical, divergent feet, nine on each coronal.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.11. Length of the single joints, a 0.02, b 0.02, c 0.05, d 0.07.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Phormocampe eucalyptra, n. sp. (Pl. [77], fig. 14).

Shell flatly conical, somewhat broader than long, with four internal annular septa. The four joints increase gradually in length and breadth. Pores subregular, hexagonal. Cephalis hemispherical, with two small, divergent horns. Peristome with a coronal of thirty to forty short, conical, divergent feet.

Dimensions.—Length of the shell 0.14, breadth 0.17. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.05.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Phormocampe metalis, n. sp.

Shell spiny, with three broad internal annular septa. Three of the four joints are nearly equal in length, each being three times as long as the first. Cephalis subspherical, with a conical horn of twice the length. The second and third joints are together nearly ellipsoidal, and are not separated externally. The fourth joint is separated from them by a deep stricture, one and a half times as broad, and flatly conical. Pores subregular, circular, hexagonally framed. Peristome with a coronal of twenty to thirty strong, conical, divergent feet.

Dimensions.—Length of the shell 0.22, basal breadth 0.16. Length of the single joint, a 0.02, b 0.06, c 0.06, d 0.08.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 2. Cyrtocorys, Haeckel, 1881, Prodromus, p. 438.

Definition.—Shell with four or more transverse strictures, and five or more joints.

5. Phormocampe mitra, n. sp.

Shell broadly campanulate, conical, about as broad as long, with five internal annular septa. Length of the six joints gradually increasing. Cephalis flat, cap-shaped, with a short, bristle-shaped, conical horn. Pores small and numerous, regular, hexagonal, with thin bars. Peristome with a coronal of forty to fifty divergent, bristle-shaped feet, about as long as the last joint.

Dimensions.—Length of the shell (with six joints) 0.16, of the last joint 0.05; breadth 0.18.

Habitat.—North Pacific, Station 235 (off Japan), surface.

6. Phormocampe conus, n. sp.

Shell slenderly conical, three times as long as broad, with thirteen distinct strictures. Length of the fourteen joints nearly equal. Breadth gradually increasing towards the mouth. Cephalis hemispherical, with a slender, conical, curved horn of three times the length. Pores small and numerous, regular, circular. Peristome with a coronal of twenty to thirty slightly divergent, bristle-shaped feet, twice as long as the last joint.

Dimensions.—Length of the shell (with fourteen joints) 0.22, of each joint (on an average) 0.016; basal breadth 0.08.

Habitat.—South Pacific, Station 297, surface.

Genus 638. Artophormis,[[255]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta) with ovate or spindle-shaped shell, bearing in its wall numerous lateral ribs, which are prolonged into terminal feet. Mouth constricted.

The genus Artophormis and the following Cyrtophormis differ from the two preceding genera in the ovate form of the shell, which tapers in breadth towards the constricted mouth. It differs from the similar Alacorys in the greater number of the shell-joints, this being four or more.

1. Artophormis horrida, n. sp. (Pl. [75], fig. 2).

Shell slenderly ovate, spiny, with three deep strictures, twice as long as broad. Length of the four joints = 2 : 5 : 6 : 7. Whole surface covered with strong conical spines. Six prominent, longitudinal ribs, decurrent from the cephalis to the mouth, are armed with larger spines, which in the upper joints are directed upwards, in the lower downwards. The six ribs are prolonged over the constricted mouth into six stout, conical feet. Cephalis subspherical, with a conical horn and some smaller spines. Pores circular, of very different sizes.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.1. Length of the single joints, a 0.02, b 0.05, c 0.06, d 0.07.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

2. Artophormis costata, n. sp.

Shell spindle-shaped, rough, with six distinct strictures, three times as long as broad. The length of the seven joints increases gradually; the last joint is twice as long as the fifth. Six prominent, radial ribs arise from the third stricture, and are prolonged into six slender, convergent, conical feet, as long as the sixth joint. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores regular, circular.

Dimensions.—Length of the shell (with seven joints) 0.24, breadth 0.08. Length of the last joint 0.05.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

3. Artophormis barbadensis, Haeckel.

Calocyclas barbadensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xviii. fig. 8.

Shell slenderly ovate, smooth, with three sharp strictures, twice as long as broad. Length of the four joints = 1 : 2 : 3 : 2. Nine prominent longitudinal ribs arise from the third joint, and are prolonged into nine slender, conical, little convergent feet. Cephalis hemispherical, with a conical horn of the same length. Pores subregular, circular, twice as large in the third joint as in the second; the fourth joint bears above a circle of nine very large pores (alternate with the nine ribs), and below two or three circles of smaller pores (eighteen to twenty-seven in the circumference). Mouth somewhat constricted. The figure of Ehrenberg is incomplete, the horn of the cephalis and the nine feet being broken off.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.08. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.04.

Habitat.—Fossil in Barbados.

Genus 639. Cyrtophormis,[[256]] n. gen.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta) with ovate or spindle-shaped shell, without lateral ribs. Mouth constricted, with a corona of terminal feet.

The genus Cyrtophormis may be derived from the preceding Artophormis by reduction of the lateral ribs, whilst the terminal feet (as their free prolongations) remain, and form a corona around the mouth. Sometimes also each constriction bears a corona of spines. It corresponds to Calocyclas among the Tricyrtida and Anthocyrtis among the Dicyrtida.

Subgenus 1. Cyrtophormium, Haeckel.

Definition.—Shell with six (sometimes five or seven) feet on the peristome (three perradial alternate with three interradial).

1. Cyrtophormis armata, n. sp. (Pl. [78], fig. 17).

Shell spiny, spindle-shaped, with three annular septa. Length of the four joints = 3 : 4 : 5 : 6. The third joint is the broadest, being twice as broad as the constricted mouth. Pores irregular, roundish. Cephalis conical, armed with a bunch of strong, conical spines, and distinguished by double-contoured pores. Peristome with six (sometimes five or seven) triangular, vertical, parallel, or slightly divergent feet.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.09. Length of the single joints, a 0.03, b 0.04, c 0.05, d 0.06.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Cyrtophormis ovata, n. sp.

Shell rough, ovate, very thick-walled, with three distinct strictures. Length of the four joints = 1 : 1 : 2 : 3. The fourth joint is the broadest, inversely hemispherical, and three times as broad as the constricted mouth. Pores regular, circular, hexagonally framed. Cephalis hemispherical, with a pyramidal horn of the same length. Peristome with a coronal of six short, conical, curved, outwardly convex teeth.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.14. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.09.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Cyrtophormiscus, Haeckel.

Definition.—Shell with nine (sometimes eight or ten) feet on the peristome (three perradial alternate with six interradial).

3. Cyrtophormis cingulata, n. sp. (Pl. [78], fig. 18).

Shell spiny, spindle-shaped, with three internal annular septa, and three external girdles of spines. The second and third joints are of nearly equal length, twice as broad as the first, and half as broad as the fourth joint. The third joint is the broadest, and twice as broad as the constricted mouth. Pores subregular, circular. Cephalis hemispherical, with a large apical horn, and a coronal of six strong ascending spines. Peristome beyond the stricture of the mouth somewhat dilated, with nine triangular, divergent teeth (broken off in the specimen figured).

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.09. Length of the single joints, a 0.02, b 0.04, c 0.04, d 0.08.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

4. Cyrtophormis aculeata, n. sp.

Shell spiny, slenderly ovate, with five distinct strictures, each with a girdle of spines. The three middle joints are of nearly equal length, each half as long as the second, and one-third as long as the sixth joint. The fifth joint is the broadest, twice as broad as the constricted mouth. Pores regular, circular. Cephalis conical, with a bunch of strong, divergent spines. Peristome with nine strong, conical, vertical, parallel teeth.

Dimensions.—Length of the shell (with six joints) 0.18, breadth 0.08. Length of the first joint 0.02, the second 0.04, the three following 0.02, the sixth 0.06.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Cyrtophormis acutata, Haeckel.

Eucyrtidium acutatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 11.

Shell rough, spindle-shaped, with six annular strictures. The third, fourth, and seventh joints are equal in length, three times as long as the first and the fifth joints. The fourth joint is the broadest, four times as broad as the constricted mouth. Pores irregular, roundish. Cephalis small, subspherical, with a short conical horn. Peristome with nine (?) irregular, triangular, little convergent teeth.

Dimensions.—Length of the shell (with seven joints) 0.22, breadth 0.11. Length of the third, fourth, and seventh joints 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr).

Subgenus 3. Acanthocyrtis, Haeckel.

Definition.—Shell with numerous (twelve to twenty or more) terminal feet.

6. Cyrtophormis cylindrica, n. sp. (Pl. [77], fig. 17).

Shell rough, subcylindrical, with three annular septa. The fourth cylindrical joint is four times as long as the second and the third joints. These three joints are nearly equal in breadth. Pores small and numerous, almost square, in regular, transverse rows; two to three in the first joint, five to six in the second and in the third, fourteen to sixteen in the fourth joint. Cephalis flat, cap-shaped, with a short, pyramidal horn. Peristome half as broad as the shell, hyaline, with a coronal of numerous, very delicate, vertical feet.

Dimensions.—Length of the shell (with four joints) 0.2, breadth, 0.08. Length of the single joints, a 0.02, b 0.03, c 0.03, d 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Cyrtophormis corona, n. sp. (Pl. [77], fig. 15).

Shell smooth, conical, ovate, with three deep strictures, about twice as long as broad. The fourth joint is the broadest, inflated, and three times as long as the second and the third joints. Pores small and numerous, circular, in regular, transverse rows; two in the first joint, four in the second and third, and ten in the fourth joint. Cephalis hemispherical, with a stout, pyramidal horn. Peristome two-thirds as broad as the fourth joint, with twelve to fifteen triangular, convergent teeth.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.08. Length of the single joints, a 0.01, b 0.03, c 0.03, d 0.09.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Cyrtophormis cornuta, n. sp. (Pl. [77], fig. 18).

Shell thorny, spindle-shaped, with three distinct strictures. Length of the four joints = 2 : 4 : 3 : 5. The third joint is the broadest. Pores circular, of different sizes, in the three first joints double-contoured. Cephalis subspherical, with a large, conical horn of three times the length. The fourth joint is inversely conical, three times as broad as the constricted mouth. Peristome with a coronal of numerous (ten to twenty) irregular, thin, partly forked teeth.

Dimensions.—Length of the shell (with four joints) 0.14, breadth 0.07. Length of the single joints, a 0.02, b 0.04, c 0.03, d 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

9. Cyrtophormis fimbriata, Haeckel.

Lithocampe fimbriata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, pl. iv. fig. 3.

Shell rough, spindle-shaped, with six annular septa. The fifth joint is the longest, twice as long as each of the three preceding joints, and four times as long as the sixth. The fourth joint is the broadest, three times as broad as the constricted mouth. Pores small, regular, circular. Cephalis small, subspherical, with a small, conical horn (broken off in the specimen figured). Peristome with an irregular, double coronal of ten to twenty vertical teeth.

Dimensions.—Length of the shell (with seven joints) 0.25, breadth 0.1. Length of the fifth joint 0.06, of each of the three preceding 0.03.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Sicily (Grotte, Caltanisetta).

10. Cyrtophormis turrita, n. sp.

Shell smooth, nearly conical, twice as long as broad, with twelve sharp strictures. The thirteen joints increase gradually in length and breadth. The last joint is much longer than any of the others, twice as long as the eleventh, and twice as broad as the ninth joint. The constricted mouth on its lower surface is only one-third as broad. Cephalis small, hemispherical, with a short, conical horn. Peristome with a coronal of twenty to thirty delicate, partly confluent, vertical teeth.

Dimensions.—Length of the shell (with thirteen joints) 0.26, breadth 0.12.

Habitat.—South-Eastern Pacific, Station 299 (off Valparaiso), depth 2160 fathoms.

11. Cyrtophormis turricula, n. sp. (Pl. [75], fig. 5).

Shell smooth, slender, tower-shaped, with fourteen distinct strictures. The ten first joints are nearly equal in length. The twelfth joint is the largest, three to four times as long as each of the preceding, and broader than all the others, twice as broad as the suddenly constricted mouth. Pores small and numerous, regular, circular, quincuncial. Cephalis small, subspherical, with a pyramidal horn of three times the length. Peristome with a coronal of twenty to thirty very delicate, partly confluent, short, vertical teeth.

Dimensions.—Length of the shell (with fifteen joints) 0.3, breadth 0.1. Length of the twelfth joint 0.05.

Habitat.—South-Eastern Pacific, Station 298 (off Valparaiso), depth 2225 fathoms.

Subfamily 2. Stichophænida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Phormocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida multiradiata clausa).

Genus 640. Artophæna,[[257]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichophænida (vel Stichocyrtida multiradiata clausa) with six radial ribs or wings.

The genus Artophæna and the following genus Stichophæna represent together the small subfamily of Stichophænida, or of those Cyrtoidea in which the multiradiate shell is composed of numerous (four or more) joints, and closed at the end by a lattice-plate. The number of the lateral, solid, or latticed appendages is six in Artophæna, nine in Stichophæna. They may have been derived either from the Stichophormida by closure of the terminal mouth, or from the Stichoperida by intercalation of three or six interradial appendages.

1. Artophæna ærostatica, n. sp. (Pl. [75], fig. 4).

Shell four-jointed, with three sharp strictures and internal septa. The fourth joint is subspherical, longer than the three first joints together, and twice as broad as these. The second joint is twice as long as the first and the third, and armed with six divergent, stout, pyramidal, radial spines or wings of the same length. Cephalis flat, cap-shaped, with an oblique pyramidal horn of twice the length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.02, d 0.1.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Artophæna senaria, n. sp.

Shell pear-shaped, with five distinct strictures. Length of the four middle joints little different. The fifth joint is the broadest. From the first stricture there arise six radial ribs, which at the fourth are prominent as six short, conical, divergent spines. The last joint is inversely hemispherical, twice as long as the preceding. Cephalis hemispherical, with a conical horn of the same length. Pores regular, circular.

Dimensions.—Length of the shell (with six joints) 0.14, breadth 0.09; of each joint 0.02, of the last 0.04.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

3. Artophæna hexalatractus, n. sp.

Shell spindle-shaped, with three sharp strictures, and six triangular, latticed, divergent wings, which arise from the collar stricture and descend along the two middle joints. Their terminal points fall into the same plane as the basal end of the fourth inversely conical joint. Length of the four joints = 1 : 2 : 4 : 2. Cephalis hemispherical, with a conical horn of the same length. (Similar to Theophæna hexaptera, Pl. [68], fig. 13, but with three distinct internal annular septa, corresponding to the three external strictures.)

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.08. Length of the four single joints, a 0.02, b 0.04, c 0.08, d 0.04.

Habitat.—South Pacific (off Juan Fernandez), Station 300, depth 1375 fathoms.

4. Artophæna hexapodiscus, n. sp.

Shell ovate, without external strictures, but with five internal annular septa. Length of the six joints = 1 : 2 : 3 : 4 : 3 : 6. Cephalis hemispherical, with a stout conical horn of twice the length. The last joint is the broadest, inversely hemispherical. From the fourth and fifth joints arise six divergent ribs, which are prolonged over the fifth stricture into six triangular, divergent, fenestrated feet, about as long as the last joint. Pores in the upper half of the shell regular, circular, in the lower half irregular, roundish.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.12. Length of the single joints, a 0.015, b 0.025, c 0.03, d 0.04, e 0.03, f 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 641. Stichophæna,[[258]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichophænida (vel Stichocyrtida multiradiata clausa) with nine radial ribs or wings.

The genus Stichophæna differs from the preceding Artophæna in the typical number of the radial lateral appendages, being nine in the former, six in the latter. Usually these are simple ribs enclosed in the shell-wall, more rarely prominent wings.

Subgenus 1. Stichophænidium, Haeckel.

Definition.—Last joint of the shell rounded, without basal spines.

1. Stichophæna ritteriana, n. sp. (Pl. [75], fig. 12).

Shell pear-shaped, twice as long as broad, with seven internal annular septa. The upper half is slenderly conical, composed of seven joints of nearly equal length, gradually increasing in breadth. The lower half is formed only by the eighth joint, which is very large, subglobose, inflated, and as long as the seven other joints together. The spherical cephalis bears a conical horn of the same length. From the thorax arise at equal distances nine radial ribs in the form of thin, triangular lamellæ, which attain their greatest height in the sixth joint, and form nine elegant, denticulate crests in the eighth joint. Pores small and numerous, subregular, circular. This beautiful species is dedicated to my honourable friend, Dr. Paul von Ritter, the magnanimous philanthropist and liberal protector of free science, who founded in the University of Jena the first professorial chair of Darwinism and phylogeny.

Dimensions.—Length of the shell (with eight joints) 0.24, breadth 0.12. Length of each of the first seven joints 0.015; diameter of the subspherical last joint 0.12.

Habitat.—South Pacific, Station 300 (off Juan Fernandez), depth 1375 fathoms.

2. Stichophæna darwiniana, n. sp.

Shell pear-shaped, twice as long as broad, with six distinct strictures. The last joint is the broadest and twice as long as the sixth, three times as long as each of the five preceding joints. The hemispherical cephalis bears a conical horn of twice the length. From the third joint arise nine radial ribs, which reach the sixth joint, but are not developed in the last hemispherical joint. Pores irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.1. Length of five first joints, each 0.018 to 0.022, of the sixth 0.03, of the seventh joint 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichophæna gœtheana, n. sp.

Shell ovate, one and a half times as long as broad, rough, with five internal annular septa. The six joints gradually increase in length and breadth. The last joint is the broadest, and half as long as the five others together. The hemispherical cephalis bears a pyramidal horn of twice the length. From the thorax arise nine radial ribs, which attain their greatest height in the fourth joint and reach the fifth joint, but are not developed in the last ovate joint. Pores subregular, circular.

Dimensions.—Length of the shell (with six joints) 0.22, breadth 0.14. Length of the single joints, a 0.02, b 0.025, c 0.03, d 0.035, e 0.04, f 0.7.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 2. Stichophænoma, Haeckel.

Definition.—Last joint of the shell pointed, armed with a polar, basal spine, or a bunch of spines.

4. Stichophæna nonaria, n. sp. (Pl. [76], fig. 6).

Shell nearly spindle-shaped, with five or six distinct strictures. The third joint is the broadest and longest, and twice as long as the second and the fifth joints. Along the second or third middle joint (beginning from the second or third) descend nine prominent longitudinal ribs. Cephalis hemispherical, with two short, conical, divergent horns. Last joint inversely conical, armed with several strong, conical, divergent spines.

Dimensions.—Length of the shell (with seven joints) 0.23, of the third joint 0.05, of the last 0.04; breadth 0.1.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Stichophæna novena, n. sp. (Pl. [76], fig. 7).

Shell nearly spindle-shaped, with eight or nine deep strictures. The third joint is the broadest, campanulate, in its lower half with nine prominent ribs, which disappear beyond the third stricture. The following joints are alternately longer and shorter, and decrease gradually in breadth. Thorax hemispherical. Cephalis small, hemispherical, with a conical horn of the same length. Last joint also hemispherical, scarcely larger than the cephalis, with a bunch of conical, divergent spines.

Dimensions.—Length of the shell (with nine joints) 0.25, of the third joint 0.05, of the last 0.02; breadth 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Family LXX. Lithocampida, n. fam.

Artocorida et Artocapsida, Stichocorida et Stichocapsida, Haeckel, 1881, Prodromus, pp. 437-439.

Definition.—Stichocyrtida eradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, without radial apophyses.)

The family Lithocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears no radial apophyses. It may be divided into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichocorida (and the united Artocorida), closed by a lattice-plate in the Stichocapsida (and the allied Artocapsida). The phylogenetic origin of the Lithocampida may be found in the Theocyrtida.

The number of species of Lithocampida is very great, and amounts here to more than one hundred and sixty whilst the total number of Stichocyrtida is about two hundred and forty. They represent therefore, two-thirds of the whole group, whilst one third is composed of the Podocampida and Phormocampida. Ehrenberg has already described between forty and fifty species in his genera Eucyrtidium and Lithocampe; the majority of these were fossils from Barbados.

This large number of species may be easily increased by accurate researches on the great masses of Lithocampida, which are found in the Radiolarian ooze of the Challenger, and as fossils in Barbados. The variety in the number, size, and proportion of the shell-joints and of the lattice-pores is very great, and permits us to distinguish a far greater number of species than are here described. Many species are cosmopolitan, and belong to the most common forms of Radiolaria.

This large number of species requires to be disposed in different genera, but the distinction of these latter is a rather difficult task, since the exterior of the shell, as well as its internal structure, offers no striking differences (compare Pls. [78] to [80]). In my Monograph (1862, pp. 312 to 319) I have already pointed out the difficulty of distinguishing between Lithocampe and Eucyrtidium. The general form of the shell exhibits a continuous series of transformations, from a flat, conical, or nearly discoidal form, through cylindrical to ovate, or spindle-shaped shells, the wide open terminal mouth becoming more or less constricted, and finally (in the Stichocapsida) closed. The absence or presence of an apical horn may further serve for the distinction of genera. A peculiar small group is represented by the Spirocampida (Spirocyrtis, Spirocampe, Pl. [76], figs. 11 to 17), the transverse latticed girdles separating the single joints, which are usually parallel and horizontal, becoming here partly connected, so that they form a descending spiral.

Synopsis of the Genera of Lithocampida.

I. Subfamily Stichocorida.

Terminal mouth of the last shell-joint a simple wide opening.

All annular septa or transverse strictures of the shell separated, parallel, not connected by a spiral line.Shell conical or cylindrical. Mouth of the last joint wide open, not distinctly constricted.Conical, gradually dilated.With horn,642. Lithostrobus.
No horn,643. Dictyomitra.
Conical above, cylindrical below.With horn,644. Stichocorys.
Cylindrical or subcylindrical.With horn,645. Artostrobus.
No horn,646. Lithomitra.
Shell ovate or spindle-shaped. Mouth of the last joint constricted.Cephalis with a horn.Last joint not tubular,647. Eucyrtidium.
Last joint a long tube,648. Eusyringium.
Cephalis without horn.Cephalis with tube.649. Siphocampe.
Cephalis without tube,650. Lithocampe.
Annular septa or transverse strictures of the shell all or partly obliquely descending and connected spirally.With horn,651. Spirocyrtis.
No horn,652. Spirocampe.

II. Subfamily Stichocapsida.

Terminal mouth closed by a lattice-plate.

Last joint rounded, without a vertical basal spine.With horn,653. Cyrtocapsa.
No horn,654. Stichocapsa.
Last joint conical, pointed, with a vertical, basal spine.Cephalis with horn,655. Artocapsa.

I. Subfamily Stichocorida.

Terminal mouth of the last shell-joint a simple wide opening.

All annular septa or transverse strictures of the shell separated, parallel, not connected by a spiral line.
Shell conical or cylindrical. Mouth of the last joint wide open, not distinctly constricted.
Conical, gradually dilated.
With horn,
642. Lithostrobus.
No horn,
643. Dictyomitra.
Conical above, cylindrical below.
With horn,
644. Stichocorys.
Cylindrical or subcylindrical.
With horn,
645. Artostrobus.
No horn,
646. Lithomitra.
Shell ovate or spindle-shaped. Mouth of the last joint constricted.
Cephalis with a horn.
Last joint not tubular,
647. Eucyrtidium.
Last joint a long tube,
648. Eusyringium.
Cephalis without horn.
Cephalis with tube.
649. Siphocampe.
Cephalis without tube,
650. Lithocampe.
Annular septa or transverse strictures of the shell all or partly obliquely descending and connected spirally.
With horn,
651. Spirocyrtis.
No horn,
652. Spirocampe.

II. Subfamily Stichocapsida.

Terminal mouth closed by a lattice-plate.

Last joint rounded, without a vertical basal spine.
With horn,
653. Cyrtocapsa.
No horn,
654. Stichocapsa.
Last joint conical, pointed, with a vertical, basal spine.
Cephalis with horn,
655. Artocapsa.

Subfamily 1. Stichocorida, Haeckel, 1881, Prodromus, p. 438.

Definition.—Lithocampida with the terminal mouth of the shell open (vel Stichocyrtida eradiata aperta).

Genus 642. Lithostrobus,[[259]] Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta), with conical shell, gradually dilated towards the wide open mouth. Cephalis with a horn.

The genus Lithostrobus is probably the most primitive among the Lithocampida, and comprises those forms of this family in which the slender, conical shell is gradually dilated towards the wide, terminal mouth, each joint being broader than the preceding. It may be derived from Theoconus by increase in the number of the joints. Some species are distinguished by a curved axis, which gives them a horn-like appearance; these may be separated as a peculiar genus, Cornustrobus.

Subgenus 1. Conostrobus, Haeckel.

Definition.—Shell regularly conical, with straight axis; all joints nearly equal in length, gradually increasing in breadth.

1. Lithostrobus monostichus, n. sp.

Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, gradually increasing in breadth; the eighth joint twice as broad as the fourth. In each joint only a single transverse series of small, circular, regular pores. Horn of the cephalis conical, straight, of twice the length. (Similar to Lithostrobus tetrastichus, Pl. [80], fig. 6, but in each joint there is only a single series of pores.)

Dimensions.—Length of the shell (with ten joints) 0.2, of each joint 0.02; breadth of the fourth joint 0.03, of the eight 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Lithostrobus distichus, n. sp.

Shell conical, papillate, with straight axis, and four to six deep strictures. All joints nearly of the same length, the fifth twice as broad as the second. In each joint two transverse rows of large, circular pores. Horn of the cephalis stout, straight, conical, of the same length.

Dimensions.—Length of the shell (with six joints) 0.18, of each joint 0.03; breadth of the second joint 0.04, of the fifth 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Lithostrobus tristichus, Haeckel.

Lithostrobus cuspidatus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium cuspidatum, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii, p. 5, pl. i. fig. 12.

Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the third. In each joint three transverse rows of pores. Horn of the cephalis bristle-shaped, strongly curved, about as long as the shell (Ehrenberg confounds this species with Lithostrobus cuspidatus).

Dimensions.—Length of the shell (with eight joints) 0.16, of each joint 0.02; breadth of the fourth joint 0.04, of the eighth 0.08.

Habitat.—North Pacific, Kamtschatka (Bailey); Station 241, depth 2300 fathoms.

4. Lithostrobus tetrastichus, n. sp. (Pl. [80], fig. 6).

Shell slenderly conical, smooth, with straight axis and six to eight deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the second. In each joint four transverse rows of regular, circular pores with very thin bars. Horn of the cephalis conical, strong, curved, about as long as two joints.

Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the second joint 0.02, of the eighth 0.04.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Lithostrobus pentastichus, n. sp.

Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth twice as broad as the third. In each joint five transverse rows of small circular pores. Horn of the cephalis pyramidal, of twice the length. (Similar to Eucyrtidium cienkowskii, Pl. [80], fig. 9, but regularly conical, with all the joints equal in length.)

Dimensions.—Length of the shell (with eight joints) 0.2, of each joint 0.025; breadth of the third joint 0.04, of the sixth 0.08.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

6. Lithostrobus hexastichus, n. sp. (Pl. [80], fig. 15).

Shell campanulate-conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth joint twice as broad as the second. In each joint six transverse rows of subregular, hexagonal pores, with thin bars. Horn of the cephalis conical, straight, of about the same length. (The specimen figured is a somewhat irregular one; other specimens found afterwards were perfectly conical and regular, with joints of equal length).

Dimensions.—Length of the shell (with six joints) 0.16, of each joint 0.027.

Habitat.—Central Pacific, Station 270 to 274, depth 2350 to 2925 fathoms.

Subgenus 2. Cornustrobus, Haeckel.

Definition.—Shell horn-shaped, conical, with curved axis; all joints nearly equal in length, gradually increasing in breadth.

7. Lithostrobus cyrtoceras, n. sp. (Pl. [80], fig. 2).

Shell horn-shaped, conical, with curved axis, smooth, with six to eight deep strictures. All joints nearly of the same length, gradually increasing in breadth; the sixth joint twice as broad as the second. In each joint about four transverse series of regular circular pores. Horn of the cephalis conical, slightly curved, of the same length.

Dimensions.—Length of the curved axis of the shell (with eight joints) 0.24, length of each joint 0.03; breadth of the second joint 0.04, of the sixth 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

8. Lithostrobus leptoceras, n. sp.

Shell horn-shaped, slenderly conical, with curved axis (like a quadrant of a circle), smooth, with twelve to fourteen slight strictures. All joints nearly of the same length, the tenth twice as broad as the second. In each joint only a single transverse row of small circular pores. Horn of the cephalis curved, bristle-shaped, half as long as the shell.

Dimensions.—Length of the curved axis of the shell (with twelve joints) 0.18, length of each joint 0.15; breadth of the second joint 0.02, of the tenth 0.04.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

9. Lithostrobus caloceras, n. sp. (Pl. [80], fig. 4).

Shell horn-shaped, conical, with curved axis, smooth, with six to eight deep strictures. All joints nearly of the same length, the sixth twice as broad as the third. On each joint a single circle of very large roundish pores, separated by two to four series of smaller pores. Horn of the cephalis conical, curved, of twice the length.

Dimensions.—Length of the curved axis of the shell (with six joints) 0.12, length of each joint 0.02; breadth of the third joint 0.04, of the sixth 0.08.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

10. Lithostrobus macroceras, n. sp.

Shell horn-shaped, slenderly conical, with curved, nearly semicircular axis, without external strictures, but with twelve to twenty internal septal rings. All joints nearly of the same length, the twelfth twice as broad as the third. On each joint three to four transverse rows of subregular, small, hexagonal pores. Horn of the cephalis conical, curved, of twice the length.

Dimensions.—Length of the curved axis of the shell (with sixteen joints) 0.32, length of each joint 0.02; breadth of the third joint 0.02, of the twelfth 0.04.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 3. Cyrtostrobus, Haeckel.

Definition.—Shell conical (often more campanulate or irregular), with straight axis; joints of different lengths. Cephalis not lobate.

11. Lithostrobus conulus, n. sp. (Pl. [80], fig. 1).

Shell slenderly conical, smooth, with straight axis, and seven to ten distinct strictures. Joints of different lengths; the fourth and fifth about twice as long as the preceding and following joints, the former with four to five, the latter with two to three transverse rows of large irregular pores; the seventh joint twice as broad as the third. Horn of the cephalis short, pyramidal.

Dimensions.—Length of the shell (with eight joints) 0.14, length of the fifth joint 0.03; breadth 0.06.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

12. Lithostrobus picus, Bütschli.

Lithostrobus picus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium picus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 1.

Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. Joints of different lengths, the second twice as long as each of the three following, and four times as long as each of the last joints; the sixth joint one and a-half times as broad as the second. Small circular pores in regular transverse rows; six rows in the first and the second, three rows in the third, fourth, and fifth, a single row in each of the last joints. Horn of the cephalis cylindrical, half as long as the shell.

Dimensions.—Length of the shell (with eight joints) 0.12, length of the second joint 0.03; breadth 0.04.

Habitat.—Fossil in Barbados.

13. Lithostrobus argus, Bütschli.

Lithostrobus argus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium argus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 1.

Shell conical, thorny, with straight axis, and five to seven slight strictures. Joints of different lengths, each of the three first twice as long as each of the following. Pores large, roundish, in transverse rows; three rows in the first and the second joints (which in the figure of Ehrenberg are not separated), two rows in the third joint, a single row in each of the following joints. Horn of the cephalis large, conical, curved, half as long as the shell.

Dimensions.—Length of the shell (with seven joints) 0.2, length of the fourth joint (and each following) 0.02; breadth 0.1.

Habitat.—Fossil in Barbados.

14. Lithostrobus acuminatus, Haeckel.

Eucyrtidium acuminatum, Bury, 1862, Polycystins of Barbados, pl. i, fig. 1.

Shell slenderly conical, smooth, with straight axis, and four to six deep strictures. Joints gradually increasing in length. Pores in regular, transverse rows, commonly three rows in the first, four in the second, five in the third, six in the fourth, seven in the fifth, &c. (sometimes the increase of the number is more or less irregular). Horn of the cephalis strong, conical, straight, about as long as the fourth or sixth joint.

Dimensions.—Length of the shell (with six joints) 0.2; length of the fourth joint 0.04, breadth 0.06.

Habitat.—Fossil in Barbados.

15. Lithostrobus cuspidatus, Haeckel.

Eucyrtidium cuspidatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ii. fig. 15.

Shell, slender, conical, smooth, with straight axis, and ten to twelve distinct strictures. Joints gradually increasing slightly in length, the tenth twice as long as the third. Pores circular, in regular transverse rows; commonly two rows in the first, three in the second, four in the third, seven in the eighth and following joints. Horn of the cephalis long, bristle-shaped, curved. This species called Eucyrtidium cuspidatum by Ehrenberg, differs from Lithostrobus tristichus (compare above), to which Bailey had given the same name.

Dimensions.—Length of the shell (with ten joints) 0.2; length of the tenth joint 0.03, breadth 0.06.

Habitat.—North Atlantic (Greenland, Ehrenberg); Station 348, depth 2450 fathoms.

16. Lithostrobus cornutella, Bütschli.

Lithostrobus cornutella, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium cornutella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ii. fig. 14.

Shell slender, conical, smooth, with straight axis, and seven to nine slight strictures. Joints gradually increasing slightly in length, the sixth or seventh about twice as long as the third. Pores circular, in regular transverse rows; two or three in the three or four first joints, three or four in the following, four or five in the last joints. Horn of the cephalis thin, bristle-shaped, curved.

Dimensions.—Length of the shell (with eight joints) 0.1; length of the eighth joint 0.01, breadth 0.04.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; many stations, surface.

17. Lithostrobus tornatus, Haeckel.

Eucyrtidium tornatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 292, Taf. ix. fig. 20.

Shell campanulate-conical, smooth, with straight axis, and four to six deep strictures. Joints broad, gradually increasing in length, the fifth twice as long as the second. Pores small, circular, in regular transverse rows; in the second and third joints three or four rows, in the fifth seven rows, &c. Horn of the cephalis small, double or forked.

Dimensions.—Length of the shell (with five joints) 0.1; length of the fifth joint 0.04, breadth 0.08.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

18. Lithostrobus seriatus, n. sp. (Pl. [79], fig. 15).

Shell slender, conical, smooth, with straight axis, and four or five deep strictures. Joints little different in length, increasing towards the inflated last joint, which is twice as long as the preceding. On each joint four or five transverse rows of small circular pores. Horn small, bristle-shaped, oblique. This common species is rather variable.

Dimensions.—Length of the shell (with five joints) 0.14; length of the fifth joint 0.05, breadth 0.06.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

19. Lithostrobus cornutus, n. sp. (Pl. [77], fig. 6).

Shell slender, conical, subcampanulate, smooth, with three or four deep strictures. Joints of different lengths, the third and the fourth twice as long as the second, four times as long as the first. Transverse rows of small circular pores; three in the first joint, five in the second, eight in the third and in the fourth. Horn large, pyramidal, about as long as the third joint.

Dimensions.—Length of the shell (with four joints) 0.12; length of the third joint 0.04, breadth 0.06.

Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms.

20. Lithostrobus microporus, Bütschli.

Lithostrobus microporus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium microporum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. xi. fig. 20.

Shell slender, conical, smooth, very similar to the preceding species, differs mainly in the more slender form and the smaller pores. The first joint has four, the second eight, the third ten transverse rows of pores. Horn conical, as long as the cephalis. The third joint in this and the preceding species is campanulate, and large.

Dimensions.—Length of the shell (with four joints) 0.11; length of the third joint 0.05, breadth 0.04.

Habitat.—Fossil in Barbados.

21. Lithostrobus quadratus, n. sp.

Shell broad, conical, smooth, with straight axis, and six to eight deep strictures. Joints of different lengths, usually alternately longer and shorter. The seventh joint five times as broad as long, twice as long as the sixth and the fourth; six transverse rows of pores in the seventh, three in the sixth joint. Horn small, conical. This species differs from all others in the subregular square form of the small pores.

Dimensions.—Length of the shell (with seven joints) 0.15; length of the seventh joint 0.024, breadth 0.12.

Habitat.—Central Pacific, Station 271 to 274, depth 2350 to 2750 fathoms.

22. Lithostrobus hexagonalis, n. sp. (Pl. [79], fig. 20).

Shell broad, conical, smooth, with straight axis, and five to eight prominent girdles between six and nine constricted broad joints. The first and the third joints are half as long as the second, the fourth, and each of the following joints. The sixth joint is five times as broad as long. Pores subregular, hexagonal, in regular transverse rows; three to four rows in the first and the second joints, six to eight in the third, the fourth, and each following joint. Cephalis with some small spines, and a larger, oblique, curved horn.

Dimensions.—Length of the shell (with six joints) 0.2; length of the sixth joint 0.04, breadth 0.2.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subgenus 4. Botryostrobus, Haeckel.

Definition.—Shell conical, with straight axis, joints of different lengths. Cephalis lobate, with some irregular constrictions. (Perhaps derived from Botryodea?).

23. Lithostrobus botryocyrtis, n. sp. (Pl. [79], figs. 18, 19).

Shell slender, conical, smooth, with straight axis, and three deep strictures. Joints of different lengths. The length of the fourth joint equals two-thirds of its breadth, and of the length of the three preceding joints together. Each of the latter bears three transverse rows of small, quadrangular pores, the fourth joint has six rows. The cephalis is irregularly lobate, with four to six prominent lobes, and two small divergent horns (fig. 19).

Dimensions.—Length of the shell (with four joints) 0.1; length of the fourth joint 0.04, breadth 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

24. Lithostrobus lithobotrys, n. sp. (Pl. [79], fig. 17).

Shell slender, conical, smooth, with straight axis, and four deep strictures. Joints of different lengths, gradually increasing towards the mouth, the length of the fifth joint equals half its breadth, and one-third of the length of the whole shell. The single joints bear each four or five transverse rows of small, roundish pores. Cephalis irregularly lobate, with four to six prominent lobes, and the same number of small, conical horns.

Dimensions.—Length of the shell (with five joints) 0.12; length of the fifth joint 0.04, breadth 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 643. Dictyomitra,[[260]] Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 80.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta), with conical shell gradually dilated towards the wide open mouth. Cephalis without horn.

The genus Dictyomitra agrees with the preceding Lithostrobus in the slender, conical form of the multiarticulate shell, but differs from it in the absence of a horn on the cephalis; the horn is here completely lost.

Subgenus 1. Dictyomitrella, Haeckel.

Definition.—Shell smooth, with joints nearly equal in length.

1. Dictyomitra articulata, Haeckel.

Eucyrtidium articulatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. figs. 2, 3.

Shell slender, conical, smooth, with six to eight deep strictures. All joints nearly equal in length, gradually increasing in breadth, the eighth four times as broad as long, and twice as broad as the fourth joint. In each joint three to four transverse series of small, regular, circular pores.

Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the fourth joint 0.04, of the eighth joint 0.08.

Habitat.—Fossil in Barbados.

2. Dictyomitra macilenta, Haeckel.

Eucyrtidium macilentum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 15.

Shell slender, conical, smooth, with five to seven deep strictures. All joints nearly equal in length, gradually increasing in breadth, the sixth joint three times as broad as long, and twice as broad as the second. In each joint only two transverse series of small, regular, circular pores.

Dimensions.—Length of the shell (with seven joints) 0.08, of each joint 0.012; breadth of the sixth joint 0.036, of the second 0.018.

Habitat.—Western Tropical Pacific, Stations 200 to 225, in various depths.

3. Dictyomitra conica, n. sp.

Shell widely conical, with six to eight prominent strictures. All joints nearly equal in length, gradually increasing in breadth, the eighth five times as broad as long, and twice as broad as the third. In each joint three to four transverse rows of regular, hexagonal pores. (Similar to Lithostrobus hexagonalis, Pl. [79], fig. 20, but more slender, and without cephalic horn.)

Dimensions.—Length of the shell (with seven joints) 0.16, of each joint 0.022; breadth of the sixth 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subgenus 2. Dictyomitrissa, Haeckel.

Definition.—Shell smooth, with joints of very different lengths.

4. Dictyomitra polypora, Zittel.

Dictyomitra polypora, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 80, Taf. ii. fig. 1.

Shell slender, conical, rough, with six to nine deep strictures. Breadth and length of the joints gradually increasing, so that the eighth joint is twice as long and broad as the third. Pores regular, circular, in transverse rows, four rows in each joint, in the last joint five to six rows.

Dimensions.—Length of the shell (with eight joints) 0.24; length of the eighth joint 0.04, breadth 0.1; length of the third joint 0.02, breadth 0.05.

Habitat.—Fossil in secondary rocks of Northern Germany (chalk of Brunswick, &c.), Zittel.

5. Dictyomitra eurythorax, n. sp. (Pl. [77], fig. 4).

Lithocampium eurythorax, Haeckel, 1881, Prodromus, p. 437, et Atlas, pl. lxxvii. fig. 4.

Shell campanulate, conical, rough, with three deep strictures. Cephalis small, hemispherical. Thorax large, inflated, hemispherical, with six transverse rows of pores. Abdomen with two broader joints, together as long as the thorax, each with three to four rows of pores.

Dimensions.—Length of the shell (with four joints) 0.14, of the thorax 0.06; breadth of the thorax 0.08, of the last joint 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Dictyomitra microcephala, Haeckel.

Eucyrtidium microcephalum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 32; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 291, Taf. xi. fig. 24.

Shell broadly conical, smooth, with six to eight distinct strictures. Breadth of the joints gradually increasing, length unequal. The three first joints short, only one-half or one-third as long as each of the following joints; in each of the former three to four transverse rows, in each of the latter six to eight transverse rows of small, regular, circular pores.

Dimensions.—Length of the shell (with six joints) 0.09, of the three first joints 0.03, of the three following 0.06; breadth of the sixth joint 0.08, of the fourth 0.04.

Habitat.—Mediterranean (Candia) Spratt, depth 1620 fathoms.

7. Dictyomitra demersissima, Haeckel.

Eucyrtidium demersissimum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 11.

Shell slender, conical, smooth, with four internal septal rings (without external strictures). Breadth of the five joints gradually increasing, length unequal; the third joint the longest, twice as long as the second, and longer than any of the following. Pores very small and numerous, in longitudinal rows.

Dimensions.—Length of the shell (with five joints) 0.09, of the second joint 0.015, of the third 0.03; breadth of the second joint 0.03, of the third 0.05.

Habitat.—Tropical Pacific, Philippine Sea, depth 3300 fathoms.

Subgenus 3. Dictyomitroma, Haeckel.

Definition.—Shell with longitudinal ribs and furrows between them, with joints of different lengths.

8. Dictyomitra costata, n. sp.

Shell slender, conical, with prominent longitudinal ribs, and six to eight deep strictures. Length of the majority of joints nearly equal, the two or three first joints shorter, the last a little longer. In each joint only a single transverse series of pores at the distal end (one pore in each furrow). (Similar to Siphocampe tubulosa, Pl. [79], fig. 13, but conical, and without cephalic tube.)

Dimensions.—Length of the shell (with eight joints) 0.16, of each middle joint 0.03, of the first 0.02; breadth of the last joint 0.06.

Habitat.—Central Pacific, Station 295, depth 1500 fathoms.

9. Dictyomitra multicostata, Zittel.

Dictyomitra multicostata, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 81, Taf. ii. figs. 2-4.

Shell slender, conical, with prominent longitudinal ribs, and eight to ten deep strictures. Length and breadth of the joints gradually increasing, the eighth joint twice as long and broad as the fourth joint. Pores regular, circular, one series in each longitudinal furrow, three to four pores on each joint.

Dimensions.—Length of the shell (with eight joints) 0.2, of the fourth joint 0.02, of the eighth joint 0.04; breadth of the fourth joint 0.04, of the eighth 0.08.

Habitat.—Fossil in secondary rocks of North Germany (chalk of Brunswick, &c.), Zittel.

Genus 644. Stichocorys,[[261]] Haeckel, 1881, Prodromus, p. 438 (sensu emendato).

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with a middle constriction of the shell, the upper half of which is conical, the lower cylindrical. Mouth truncate. Cephalis with a horn.

The genus Stichocorys is intermediate between the two preceding and the two following genera; the upper half of the shell with the three first joints is conical, the lower half with the fourth and the following joints cylindrical, of equal breadth. The third joint of the shell (or the abdomen of Theoconus) is constantly the largest, being broader than all the other joints. Stichocorys is a very common and characteristic form, and may be derived from Theoconus by development of a post-abdomen.

1. Stichocorys wolffii, n. sp. (Pl. [80], fig. 10).

Shell in the upper half (with three joints) thorny, in the lower half (with two joints) smooth. Pores of the former double-contoured, in subregular, transverse rows. Pores of the latter smaller, simple, scarcely scattered. Cephalis with a pyramidal horn of the same length. Thorax with prominent, longitudinal divergent ribs. Dedicated to Caspar Friedrich Wolff (Halle, 1759).

Dimensions.—Length of the shell (with five joints) 0.16; breadth of the third joint 0.08, of the fourth 0.05.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Stichocorys panderi, n. sp. (Pl. [80], fig. 7).

Shell in the upper conical half (with three joints) spiny, in the lower subcylindrical half (with three joints) smooth. Pores small, circular, irregularly scattered, simple. Cephalis with a conical horn of the same length. No longitudinal ribs. Dedicated to Christian Pander (Würzburg, 1817.)

Dimensions.—Length of the shell (with six joints) 0.18; breadth of the third joint 0.08, of the fourth 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichocorys baerii, n. sp. (Pl. [80], fig. 8).

Shell in the upper conical half (with three joints) spiny, in the lower cylindrical half (with three joints) sulcate, with prominent longitudinal ribs, alternating with longitudinal rows of small pores. Pores of the upper half smaller, quincuncially disposed. Cephalis with a stout pyramidal horn of the same length. Dedicated to Carl Ernst Baer (Königsberg, 1828).

Dimensions.—Length of the shell (with six joints) 0.2; breadth of the third joint 0.09, of the fourth 0.07.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Stichocorys okenii, n. sp. (Pl. [80], fig. 5).

Shell smooth, without spines or ribs; the upper conical half (with three joints) about the same length as the lower subcylindrical half (with three joints). Pores subregular, circular, in the inflated third joint twice as large as in the five other joints. At the lumbar stricture (between the second and third joints) a coronal of nine very large pores. Cephalis with a curved horn of half the length. Dedicated to Lorenz Oken (Jena, 1806).

Dimensions.—Length of the shell (with six joints) 0.2; breadth of the third joint 0.09, of the fourth 0.07.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Stichocorys huschkei, n. sp. (Pl. [80], fig. 3).

Shell in the upper conical half (with three joints) thorny, in the lower cylindrical half (with five joints) smooth, roundish. Pores irregularly scattered, always double-contoured, in the second joint three times as large as in the third. At the third stricture (between the third and fourth joints) a coronal of larger pores. Cephalis with a small, conical horn of half the length. No longitudinal ribs. Dedicated to Emil Huschke (Jena, 1832).

Dimensions.—Length of the shell (with eight joints) 0.18; breadth of the third joint 0.08, of the fourth joint 0.07.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

6. Stichocorys rathkei, n. sp.

Shell spiny, everywhere covered with short conical spines. The upper conical part of the shell (with three joints) half as long as the lower cylindrical part (with six joints). Pores irregular, roundish, in the thorax twice to three times as large as in the eight other joints. Cephalis with a pyramidal horn of the same length. No longitudinal ribs. Dedicated to Heinrich Rathke (Königsberg, 1839).

Dimensions.—Length of the shell (with nine joints) 0.24; breadth of the third joint 0.08, of the fourth joint 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

7. Stichocorys mülleri, n. sp.

Shell in the upper conical part (with three joints) spiny, in the lower cylindrical part (with seven joints) smooth. Pores in the former irregularly scattered, roundish, in the latter circular, regularly disposed in longitudinal series, alternate, with prominent ribs. The upper conical part of the shell is about half as long as the lower cylindrical part. Cephalis with a large, pyramidal horn of three times the length. Dedicated to Johannes Müller (Berlin, 1858).

Dimensions.—Length of the shell (with ten joints) 0.22; breadth of the third joint 0.09, of the fourth joint 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 645. Artostrobus,[[262]] n. gen.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis with a horn.

The genus Artostrobus and the following Dictyomitra differ from all the other Stichocorida in the cylindrical or nearly cylindrical form of the shell, all the joints of which are nearly equal in breadth, and are very short, often with a single transverse row of pores only. The first joint or cephalis is usually different from the following, often hemispherical or cap-shaped joints. The last joint is truncate, and has a wide open mouth. Since the constrictions between the single joints are often very slight, some species are very similar to the Dicyrtide Sethocorys.

Subgenus 1. Artostrobulus, Haeckel.

Definition.—A single transverse row of small, circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)

1. Artostrobus annulatus, Haeckel.

Cornutella annulata, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. pl. i. fig. 5a, 5b.

Eucyrtidium annulatum, Haeckel, 1862, Monogr. d. Radiol., p. 327.

Shell slender, cylindrical, smooth, without external strictures, but with ten to twenty internal annular septa. On each joint only a single transverse row of small pores. Cephalis hemispherical, with a single or double small horn. Each joint about four times as broad as long.

Dimensions.—Length of the shell (with twenty joints) 0.2; length of each joint 0.01, breadth 0.04.

Habitat.—Arctic Ocean, Kamtschatka (Bailey); Greenland (Ehrenberg).

2. Artostrobus elegans, Haeckel.

? Eucyrtidium elegans, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, pl. xi. fig. 12.

? Eucyrtidium pauperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, pl. xi. fig. 13.

Shell cylindrical, smooth, with eight to ten internal annular septa. Cephalis subspherical, with a short, conical horn. Thorax campanulate, with two transverse rows of pores. Abdomen with six to eight equal joints, each with a single row of pores. (May be described, perhaps, better as Theocyrtis elegans. Eucyrtidium pauperum, Ehrenberg, loc. cit., may be a variety of this species.)

Dimensions.—Length of the shell (with nine joints) 0.1; length of each abdominal joint 0.01, breadth 0.03.

Habitat.—Fossil in Barbados.

Subgenus 2. Artostrobium, Haeckel.

Definition.—All (or the majority) of the joints of the shell with several transverse rows of pores, in variable number.

3. Artostrobus auritus, Haeckel.

Lithocampe aurita, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Lithocampe auricula, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 71.

Eucyrtidium auritum, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 25.

Eucyrtidium auritum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 104, Taf. iv. fig. 7.

Shell subcylindrical, with five sharp strictures. All six joints nearly equal in length; each with four or five transverse rows of small pores. Cephalis small, flat, hemispherical, with two or three small, conical, oblique horns. Mouth of the sixth joint a little constricted.

Dimensions.—Length of the shell (with six joints) 0.12; length of each joint (on an average) 0.02, breadth 0.04 to 0.05.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).

4. Artostrobus biseriatus, n. sp.

Shell cylindrical, smooth, with ten to twelve deep strictures. All joints nearly equal in size; each with two transverse rows of small circular pores. Cephalis hemispherical, with a long, bristle-shaped, curved horn.

Dimensions.—Length of the shell (with twelve joints) 0.24; length of each joint 0.02, breadth 0.04.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

5. Artostrobus articulatus, n. sp. (Pl. [79], fig. 16).

Shell subcylindrical, with elegant longitudinal ribs and five sharp strictures. All six joints nearly equal in length, each with three or four transverse rows of small circular pores. The middle joints twice as broad as long. Cephalis hemispherical with a conical, oblique horn.

Dimensions.—Length of the shell (with six joints) 0.16, length of a single joint 0.02 to 0.03, breadth 0.04 to 0.05.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

Genus 646. Lithomitra,[[263]] Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 529.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis without horn.

The genus Lithomitra differs from the preceding genus Artostrobus in the absence of a cephalic horn, and therefore bears to it the same relation as Dictyomitra does to Lithostrobus. In many species the joints are very short, and bear only a single transverse row of pores, and since the constrictions between the joints are often very slight, Lithomitra becomes very similar to the Dicyrtide Dictyocephalus.

Subgenus 1. Lithomitrella, Haeckel.

Definition.—A single transverse row of small circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)

1. Lithomitra pachyderma, Bütschli.

Lithomitra pachyderma, Bütschli, 1882, Zeitschr. f. wiss. Zool., Vol. xxxvi. p. 529.

Eucyrtidium pachyderma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 21.

Eucyrtidium imbricatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 22.

Shell thick-walled, subcylindrical, with longitudinal ribs, slightly dilated in the middle, with ten to twelve subequal joints. On the lower edge of each joint a single row of small circular pores. No external strictures. This and the following species (though separated by Ehrenberg as four different species) may be united.

Dimensions.—Length of the shell (with ten joints) 0.11; length of each joint 0.01 to 0.012, breadth 0.04.

Habitat.—Fossil in Barbados.

2. Lithomitra acephala, Bütschli.

Lithomitra acephala, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium acephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 5.

Eucyrtidium obstipum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 17.

Shell nearly cylindrical, smooth, thick-walled, with twelve to sixteen subequal joints. On each joint a single row of small circular pores. No external strictures. Scarcely differing from the preceding species; the joints are broader and shorter, the cephalis is larger (by union of some joints?), and the ribs of the surface less distinct.

Dimensions.—Length of the shell (with twelve joints) 0.1; length of each joint 0.006 to 0.009, breadth 0.04.

Habitat.—Fossil in Barbados.

3. Lithomitra lineata, Haeckel.

Lithocampe lineata, Ehrenberg (partim), 1838, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 130; Mikrogeol., 1854, Taf. xxii. fig. 26.

Lithocampe lineata, Haeckel, 1862, Monogr. d. Radiol., p. 316.

Eucyrtidium lineatum, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xxxvi. fig. 16; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. xi. fig. 9.

Dictyomitra lineata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 101, Taf. iii. fig. 22.

Shell subcylindrical, smooth, with longitudinal ribs, and four to eight slight transverse strictures. Cephalis small, subspherical, with few small pores. Thorax broader, with two or three transverse rows of pores. Each succeeding (abdominal) joint with a single transverse row of small pores. Variable and nearly related to the two preceding species (compare my Monograph, loc. cit.).

Dimensions.—Length of the shell (with six to eight joints) 0.06 to 0.08; length of each joint (on an average) 0.01, breadth 0.03.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, in various depths; many stations; fossil in Secondary and Tertiary rocks of many places.

4. Lithomitra nodosaria, n. sp. (Pl. [79], fig. 1).

Shell subcylindrical, with longitudinal ribs, and five to eight transverse strictures, and prominent girdles between them. On each girdle (at the lowermost edge of each joint) a single transverse row of circular pores. The three or four uppermost joints are united, and represent a conical cephalis.

Dimensions.—Length of the shell (with six joints) 0.1; length of each joint 0.01 to 0.15, breadth 0.04 to 0.06.

Habitat.—Central Pacific, Station 263 to 274, depth 2350 to 2925 fathoms.

5. Lithomitra eruca, n. sp. (Pl. [79], fig. 3).

Shell subcylindrical, diminishing slightly towards both ends, with ten to fifteen slight strictures. On each joint a single transverse row of circular pores, descending obliquely in the wall. The two or three first joints form together a roundish cephalis. Usually each joint is three times as broad as long.

Dimensions.—Length of the shell (with twelve joints) 0.2; length of each joint (on an average) 0.016, breadth 0.05.

Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

6. Lithomitra chrysalis, n. sp. (Pl. [79], fig. 4).

Shell subcylindrical, diminishing slightly towards both ends, with elegant longitudinal ribs, and with five to eight slight strictures. Each of the upper joints with two (or sometimes three) transverse rows of small pores; each of the lower joints with only a single row.

Dimensions.—Length of the shell (with six joints) 0.11; length of each joint 0.01 to 0.015, breadth 0.04 to 0.05.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 2. Lithomitrissa, Haeckel.

Definition.—All (or the majority) of the joints of the shell with several transverse rows of pores, in variable number.

7. Lithomitra cylindrica, n. sp.

Shell cylindrical, smooth, with twelve to sixteen internal septal rings (without external strictures). On each joint two transverse rows of small, regular, circular pores. The hemispherical cephalis also has two rows of pores. Each joint is twice as broad as long.

Dimensions.—Length of the shell (with sixteen joints) 0.3; length of each joint 0.02, breadth 0.04.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

8. Lithomitra costata, Haeckel.

Dictyomitra costata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 101, Taf. iii. fig. 23.

Shell with longitudinal ribs, in the upper half conical, in the lower half cylindrical, with six to eight slight strictures. Small, circular pores in regular transverse rows; three rows in each upper joint, two rows in each lower joint (the last joints sometimes confluent).

Dimensions.—Length of the shell (with eight joints) 0.15; length of each joint 0.017 to 0.023, breadth 0.04 to 0.05.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr), Caltanisetta (Haeckel).

9. Lithomitra punctata, Haeckel.

Lithocampe punctata, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Eucyrtidium punctatum, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 24.

Dictyomitra punctata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 101, Taf. iii. fig. 24.

Shell subcylindrical, smooth, with four to six distinct strictures. Cephalis small, subspherical. Thorax campanulate-conical. Abdomen cylindrical, with three to four equal joints. In each joint five to six transverse rows of small, circular pores, quincuncially disposed.

Dimensions.—Length of the shell (with five joints) 0.1; length of each joint (except the first) 0.02, breadth 0.05.

Habitat.—Fossil in Tertiary rocks of Sicily; Caltanisetta (Ehrenberg), Grotte (Stöhr).

10. Lithomitra seriolata, Haeckel.

Eucyrtidium seriolatum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 33.

Lithocampe seriolata, Haeckel, Monogr. d. Radiol., p. 316.

Shell subcylindrical, smooth, with four to six sharp strictures. Cephalis small, hemispherical. Thorax conical. Abdomen cylindrical, with three to five different joints of alternate sizes. Small circular pores in transverse rows; three or four rows in the third and fifth joints, seven or eight rows in the second, fourth, and sixth joints.

Dimensions.—Length of the shell (with six joints) 0.1; length of the second and fourth joints 0.03, of the third and fifth joints 0.015.

Habitat.—Mediterranean, Crete (Ehrenberg), Corfu (Haeckel).

11. Lithomitra hyperborea, Haeckel.

Eucyrtidium hyperboreum, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii., pl. i. fig. 10.

Lithocampe hyperborea, Haeckel, 1862, Monogr. d. Radiol., p. 315.

Shell cylindrical, with prominent longitudinal ribs and six deep strictures. Cephalis hemispherical. On each joint three to four transverse rows of small, obsolete pores. Each joint is about twice as broad as long.

Dimensions.—Length of the shell (with six joints) 0.12; length of each joint 0.02, breadth 0.04.

Habitat.—Arctic and Northern Pacific, Kamtschatka (Bailey).

12. Lithomitra australis, Haeckel.

Lithocampe australis, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 187.

Lithocampe australis, Haeckel, 1862, Monogr. d. Radiol., p. 315.

Eucyrtidium australe, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xxxv., A 21, fig. 18.

Shell subcylindrical, smooth, with five deep strictures. The two middle joints somewhat larger than the two proximal and the two distal joints. Pores small, circular, in regular, transverse rows; two rows in the first and the sixth joints, five rows in the second and the fifth, seven or eight rows in the third and fourth joints. The two latter are twice as broad as long.

Dimensions.—Length of the shell (with six joints) 0.14; length of the four smaller joints 0.017, of the two larger joints 0.035; breadth 0.06.

Habitat.—Antarctic Sea (lat. 78° 10′ S., long. 162° W.) Ross.

13. Lithomitra eminens, Haeckel.

Lithocampe eminens, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iv. fig. 2.

Shell subcylindrical, rough, with seven slight strictures. The two or three middle joints half as long as the two preceding and the two following joints. Cephalis small, subspherical. Pores small, in subregular, transverse rows, on the fifth and sixth joints only two rows, on the second, third, seventh, and eighth joints four to five rows.

Dimensions.—Length of the shell (with eight joints) 0.27; length of the fifth and sixth joints 0.17, of the others 0.03 to 0.04; breadth 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr).

14. Lithomitra infundibulum, n. sp. (Pl. [79], fig. 5).

Shell in the upper half subconical, in the lower half subcylindrical, rough, with four slight strictures. Cephalis hemispherical. Thorax conical. Abdomen subcylindrical, three-jointed. Pores of the second, third, and fourth joints funnel-shaped, with very small inner, and larger double-contoured outer aperture; on the thorax twelve transverse rows, on the third and fourth joints five rows. Fifth joint with irregular, polygonal pores.

Dimensions.—Length of the shell (with five joints) 0.2; length of the thorax 0.06, breadth 0.08; length of each abdominal joint 0.04, breadth 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 647. Eucyrtidium,[[264]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Stichocorida (vel Stichocyrtida eradiate aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis with a solid horn.

The genus Eucyrtidium (as here stated in the definition) and the three following nearly allied genera differ from the preceding Stichocorida in the more or less constricted mouth, and the consequent ovate or spindle-form of the multiarticulate shell. The middle joints of the latter are broader than the upper and the lower joints. In the earlier definition given in my Monograph (1862, pp. 312 to 320), the genus had a much wider sense; but the very large number of species since detected requires a more strict definition. Ehrenberg confounded in his genus Eucyrtidium a large number of very different Cyrtoidea. In his last works (1872, 1875) he described not less than one hundred and eleven species, fifty-five fossil and fifty-six living (eight fossil species being yet living). But, in reality, these one hundred and three species belong to twenty or twenty-two very different genera of Cyrtoidea.

Subgenus 1. Eucyrtis, Haeckel, 1881, Prodromus, p. 438.

Definition.—All joints of the shell nearly of the same length (excepting often the first). Surface smooth or rough, without spines.

1. Eucyrtidium acuminatum, Ehrenberg.

Eucyrtidium acuminatum, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xii. fig. 27.

Eucyrtidium acuminatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 104, Taf. iv. fig. 6.

Eucyrtidium acuminatum, Haeckel, 1862, Monogr. d. Radiol., p. 326.

Lithocampe acuminata, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Shell smooth, slender, nearly spindle-shaped, without external strictures, but with eight to nine internal septal rings. All joints (except the first) nearly of the same length (or the upper somewhat longer). The fifth joint is the broadest. Cephalis small, subspherical, with a short, conical horn. Pores very small and numerous, regular, hexagonal, four to six on the length of each joint.

Dimensions.—Length of the shell (with eight joints) 0.14; length of each joint about 0.02; greatest breadth, in the fifth joint, 0.07.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta, Grotte, &c.).

2. Eucyrtidium tropezianum, Haeckel.

Lithocampe tropeziana, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 42, Taf. vii. figs. 4, 5, 6.

Lithocampe tropeziana, Haeckel, 1862, Monogr. d. Radiol., p. 326.

Shell smooth, slender, nearly spindle-shaped, without external strictures, but with seven or eight internal septal rings. All joints of the same length. The fifth and sixth joints are the broadest. Cephalis hemispherical, with a pyramidal horn of the same length. Pores very small and numerous, regular, circular, hexagonally framed, five to six in the length of each joint. (Very near to the preceding species, but more regular, and with different pores.)

Dimensions.—Length of the shell (with eight joints) 0.16, length of each joint 0.02; greatest breadth (in the fifth joint) 0.07.

Habitat.—Mediterranean, French shore, St. Tropez (J. Müller), surface.

3. Eucyrtidium hexagonatum, n. sp. (Pl. [80], fig. 11).

Shell smooth, ovate, with six to seven internal septal rings. All joints (except the first) nearly of the same length; the sixth joint is the broadest. The seventh and eighth joints (broken off in the specimen figured) gradually decrease toward the constricted mouth, which is as broad as the septum between the third and fourth joints. Cephalis and thorax together pear-shaped, with circular pores, sharp lumbar stricture, and a stout, pyramidal horn of the same length. The five or six abdominal joints with regular, hexagonal pores, six or seven in course of the length of each joint.

Dimensions.—Length of the shell (with eight joints) 0.2, length of each joint 0.025 to 0.03; greatest breadth (in the sixth joint) 0.1.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

4. Eucyrtidium fusiforme, n. sp.

Shell smooth, slender, spindle-shaped, without external strictures, but with ten to twelve internal septal rings. All joints of the same length; the sixth joint is the broadest. Cephalis conical, with a pyramidal horn of the same length. Pores regular, circular, four or five in course of the length of each joint. (Differs from all other species of the genus in the regular, slender, spindle form; the constricted mouth of the last joint is half as broad as the sixth joint.)

Dimensions.—Length of the shell (with twelve joints) 0.24, length of each joint 0.02; greatest breadth (on the sixth joint) 0.06, of the mouth 0.03.

Habitat.—Indian Ocean, Maldive Islands (Haeckel, 1882), surface.

5. Eucyrtidium doliolum, n. sp.

Shell smooth, barrel-shaped, or nearly spindle-shaped, with eight or nine distinct strictures. All joints (except the first) of the same length; the fourth joint is the broadest. Cephalis small, subspherical, with two short, divergent, conical horns. Pores regular, circular, hexagonally framed, three to four in course of the length of each joint.

Dimensions.—Length of the shell (with ten joints) 0.2, length of each joint 0.022; greatest breadth (in the fourth joint) 0.08.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Subgenus 2. Stichocyrtis, Haeckel, 1881, Prodromus, p. 438.

Definition.—All joints of the shell nearly of the same length (excepting often the first). Surface spiny.

6. Eucyrtidium spinosum, n. sp.

Shell spiny, slender, ovate, without external strictures, but with seven or eight internal septal rings. Conical spines of different lengths are scattered over the whole surface. All joints have nearly the same length; the sixth is the broadest. Cephalis conical, with one large and two or three smaller conical horns. Mouth constricted, half as broad as the shell. Pores irregular, roundish, double-edged, three to four on the length of each joint.

Dimensions.—Length of the shell (with eight joints) 0.16, length of each joint 0.02; greatest breadth (on the sixth joint) 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

7. Eucyrtidium chrysalidium, n. sp.

Shell spiny, spindle-shaped, with four to five slight strictures, above each stricture a circle or girdle of conical spines (as in the similar Cyrtophormis cingulata, Pl. [78], fig. 18). All joints (except the first) have the same length. Cephalis subspherical, with a bunch of divergent spines. Mouth constricted, only one-third as broad as the third joint, which is the broadest. Pores subregular, circular, four to five on the length of each joint.

Dimensions.—Length of the shell (with six joints) 0.18, length of each joint 0.032; greatest breadth 0.08.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

Subgenus 3. Artocyrtis, Haeckel.

Definition.—Joints of the shell of very different lengths. Surface smooth or rough, without spines.

8. Eucyrtidium profundissimum, Ehrenberg.

Eucyrtidium profundissimum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 12.

Shell smooth, campanulate, ovate, with three internal septal rings. Four joints of different lengths. Cephalis subspherical, with a small bristle-shaped horn. Thorax campanulate, nearly twice as long as each of the two following joints, which are nearly equal in breadth. Terminal mouth wide open, little constricted. Pores very small and numerous, regular, hexagonal.

Dimensions.—Length of the shell (with four joints) 0.12; length of the thorax 0.05, breadth 0.07.

Habitat.—Pacific; many Stations (Stations 206, 225, 253, 265, &c.), in depths between 2000 and 4000 fathoms.

9. Eucyrtidium anthophorum, Haeckel.

Thyrsocyrtis anthophora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 9.

Shell smooth, slender, ovate, with three slight strictures. Four joints of different lengths. Cephalis subspherical, with a stout, club-shaped, spinulate or branched horn of the same length. Second campanulate and third subcylindrical joint about equal in size. Fourth joint only half as long, with slightly constricted mouth (broken off in Ehrenberg's figure). Pores small and numerous, regular, circular, quincuncial.

Dimensions.—Length of the shell (with four joints) 0.12; length of the second and of the third joints 0.04, breadth 0.05 to 0.06.

Habitat.—Fossil in Barbados.

10. Eucyrtidium hertwigii, n. sp. (Pl. [80], fig. 12).

Shell smooth, ovate, truncate, with three distinct strictures. Four joints of different lengths. Cephalis campanulate, with an internal rod-cross, and a stout pyramidal horn of the same length. Second joint campanulate. Third joint larger, subcylindrical, with a variable number of irregular, longitudinal ribs, some of which are prolonged into the second and fourth joints. The latter is only half as long, and slightly constricted towards the mouth. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.22. Length of the single joints, a 0.03, b 0.06, c 0.08, d 0.05; breadth, a 0.03, b 0.1, c 0.12, d 0.11.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

11. Eucyrtidium lagena, Haeckel.

Eucyrtidium lagena, Haeckel, 1862, Monogr. d. Radiol., p. 325, Taf. iv. fig. 11.

Lithocampe lagena, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 839.

Shell smooth, bottle-shaped, with three distinct strictures. Four joints of different sizes. Cephalis small, spherical, with a bristle-shaped horn of the same length. Second joint conical, third subcylindrical, fourth inflated, with slightly constricted mouth; their lengths about equal. Pores subregular, hexagonal, large, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.16; length of each of the three lower joints about 0.05, breadth 0.05 to 0.064.

Habitat.—Mediterranean (Messina).

12. Eucyrtidium teuscheri, n. sp. (Pl. [77], fig. 5).

Shell smooth, bottle-shaped, with three distinct strictures. Four joints of different lengths. The third joint four times as long as each of the two first joints, and longer than the fourth, which is little constricted towards the mouth. The greatest breadth is in the middle of the shell. Cephalis hemispherical, with a small, conical horn of the same length. Pores large, circular, of variable sizes. Dedicated to Dr. Reinhold Teuscher.

Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.015, b 0.02, c 0.07, d 0.055; breadth, a 0.03, b 0.05, c 0.08, d 0.06.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

13. Eucyrtidium bütschlii, n. sp. (Pl. [77], fig. 7).

Shell rough, slender, ovate, truncate, with three distinct strictures. Four joints of different lengths; the third is the largest, inflated, subspherical. Fourth joint subcylindrical, little constricted towards the truncate mouth. Cephalis hemispherical, with a small, conical horn. Pores circular, much larger in the third joint than in the three others.

Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.05; breadth, a 0.03, b 0.07, c 0.09, d 0.07.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

14. Eucyrtidium galatheæ, Ehrenberg.

Eucyrtidium galatheæ, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 242.

Shell smooth, campanulate, with three deep strictures. Four joints of different lengths; the fourth joint is the broadest, twice as long as the third and the second, three times as long as the hemispherical cephalis, which bears a stout, pyramidal, oblique horn of twice the length. Mouth little constricted. Pores regular, circular, in transverse rows, three rows in each of the three first joints, five or six rows in the last joint.

Dimensions.—Length of the shell (with four joints) 0.12; length of the fourth joint 0.05, breadth 0.07.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

15. Eucyrtidium galea, Haeckel.

Eucyrtidium galea, Haeckel, 1862, Monogr. d. Radiol., p. 324, Taf. vii. figs. 8-10.

Lithocampe galea, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 838.

Shell smooth, helmet-shaped, with four sharp strictures. Five joints of different lengths. Cephalis small, spherical, with a thin pyramidal horn of the same length. Second joint conical, about as long as the third, longer than the fourth and the fifth joints. The third joint is the broadest. Pores regular, circular, small and numerous.

Dimensions.—Length of the shell (with five joints) 0.18; length of the second and the third joints 0.05, of the fourth 0.03; breadth 0.08 to 0.1.

Habitat.—Mediterranean (Messina), surface.

16. Eucyrtidium eruca, Ehrenberg.

Eucyrtidium eruca, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 13.

Shell smooth, slender, ovate, or nearly spindle-shaped, with four sharp strictures. Five joints of different lengths, the third and fourth nearly equal, twice as long as the fifth, one and a half times as long as the second; the fourth joint is the broadest. Mouth little constricted. Cephalis subspherical, with a small, conical horn. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with five joints) 0.12 to 0.14; length of the third and the fourth joints, 0.03 to 0.04, breadth 0.04 to 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific, in different depths; also fossil in Barbados and Sicily.

17. Eucyrtidium montiparum, Ehrenberg.

Eucyrtidium montiparum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 11.

Shell rough, nearly spindle-shaped, with five deep strictures. Six joints of different lengths, the third and fourth nearly equal, longer than the fifth and the sixth joints; the fourth joint is the broadest. Mouth slightly constricted. Cephalis very small, hemispherical, hyaline, with a short, conical horn. Pores subregular, circular, twice as broad as in the similar smaller preceding species.

Dimensions.—Length of the shell (with six joints) 0.2; length of the third and the fourth joints 0.05, breadth 0.07 to 0.08.

Habitat.—Fossil in Barbados.

18. Eucyrtidium cienkowskii, n. sp. (Pl. [80], fig. 9).

Shell smooth, subconical, with five distinct strictures. Six joints of different lengths; the third joint conical, one and a half to two times as long as each of the other joints; the fifth joint is the broadest. Mouth wide, very slightly constricted. Cephalis hemispherical, with an oblique pyramidal horn of the same length. Pores regular, circular, in dense transverse rows; five to six rows in each of the three last joints, eight to nine rows in the third joint.

Dimensions.—Length of the shell (with six joints) 0.16, length of the third joint 0.04, of each following joint 0.02; greatest breadth (in the fifth joint) 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

19. Eucyrtidium elongatum, Stöhr.

Eucyrtidium elongatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 10.

Shell rough, slender, nearly spindle-shaped, variable in size and form, with six to seven distinct strictures. Seven to eight joints of different lengths, often alternately longer and shorter. The second and the last joints are the longest, the third is the broadest. Mouth slightly constricted (broken off in Stöhr's figure). Cephalis small, subspherical, with a small, oblique, curved horn. Pores irregular.

Dimensions.—Length of the shell (with seven joints) 0.2; length of the single joints, between 0.02 and 0.04, breadth 0.06 to 0.08.

Habitat.—Fossil in Sicily (Grotte, Caltanisetta).

20. Eucyrtidium stöhrii, n. sp.

Shell smooth, spindle-shaped, gradually diminishing towards both ends, with eight to ten distinct strictures. Nine to eleven joints of different lengths; the two or three middle joints—fifth, sixth, and seventh—longer and broader than the other joints; the broadest is the fifth joint, which is twice to three times as long as the first and last joints. Cephalis subspherical, with a conical horn of the same length. Terminal mouth strongly constricted, one-half or one-third as broad as the fifth joint. Pores small, regular, circular.

Dimensions.—Length of the shell (with ten joints) 0.22; length of the largest (fifth joint) 0.03, breadth 0.09.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

21. Eucyrtidium scalarium, n. sp.

Shell smooth, slender, ovate, with nine to ten deep strictures, and ten to eleven separate step-like joints of different lengths. The sixth joint is the longest, twice as long as the fourth, and three times as long as the third and the last joint; the seventh and eighth joints are the broadest, one and a half times as broad as the wide mouth. Cephalis hemispherical, with a short pyramidal horn of the same length. Pores small and numerous, subregular, square, in regular transverse rows; six rows in the sixth joint, three rows in the last joint. (Somewhat similar to Spirocyrtis scalaris, Pl. [76], fig. 14, but ovate, not conical and not spiral.)

Dimensions.—Length of the shell (with eleven joints) 0.22, breadth 0.11; length of the last joint 0.01, of the sixth 0.03.

Habitat.—North Atlantic, Station 64, surface.

Subgenus 4. Acanthocyrtis, Haeckel, 1881, Prodromus, p. 437.

Definition.—Joints of the shell of very different lengths. Surface spiny.

22. Eucyrtidium tricinctum, n. sp. (Pl. [78], fig. 13).

Shell spiny, spindle-shaped, with three distinct strictures. Four joints of different lengths, the first and third half as long as the second and fourth; the third joint is the broadest, four times as broad as the strongly constricted mouth. Spines irregularly scattered over the lower half of the shell, increasing in size towards the mouth. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.25. Length of the single joints, a 0.03, b 0.08, c 0.04, d 0.09; breadth (of the third joint) 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

23. Eucyrtidium armatum, n. sp. (Pl. [78], fig. 14).

Shell spiny, spindle-shaped, with three distinct strictures. Four joints of different lengths, the second and third joints of the same length, shorter than the fourth joint; the third joint is the broadest, four times as broad as the strongly constricted mouth. The latter, as well as the conical cephalis, is armed with an irregular bunch of strong conical spines, while numerous smaller spines are scattered over the whole surface. Pores irregular, roundish, double-contoured.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.05, c 0.05, d 0.08; breadth (of the third joint) 0.1.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

24. Eucyrtidium conostoma, n. sp. (Pl. [78], fig. 16).

Shell spiny, spindle-shaped, with four distinct strictures. Five joints of different lengths, having the proportion = 1 : 2 : 3 : 6 : 10. The fourth joint is the broadest, inflated, twice as broad as long. Cephalis small, with a conical horn of the same length. Fifth joint inversely conical, with a narrow mouth, broader than the cephalis. Short conical spines are scattered over the whole surface. Pores subregular, circular.

Dimensions.—Length of the shell (with five joints) 0.22. Length of the single joints, a 0.01, b 0.02, c 0.03, d 0.06, e 0.1; breadth (of the fourth joint) 0.09.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

25. Eucyrtidium ehrenbergii, n. sp. (Pl. [78], fig. 15).

Shell spiny, spindle-shaped, with four distinct strictures (the first and the fourth are by a mistake not distinctly figured). Five joints of different lengths, having the proportion = 2 : 3 : 4 : 2 : 5. The third joint is the broadest, twice as broad as long, and twice as broad as the constricted mouth. Whole surface covered with strong spines. Pores irregular, roundish.

Dimensions.—Length of the shell (with five joints) 0.16. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.02, e 0.05; breadth (in the third joint) 0.08.

Habitat.—Western Tropical Pacific, Station 220, depth 1100 fathoms.

26. Eucyrtidium ovatum, n. sp.

Shell spiny, inversely ovate, with five sharp strictures. Six joints of different lengths, having the proportion = 1 : 3 : 2 : 1 : 1 : 3. The third joint is the broadest, three times as broad as the constricted mouth. Cephalis with a stout pyramidal horn of the same length. Whole surface spiny. Pores irregular, roundish.

Dimensions.—Length of the shell (with six joints) 0.22. Length of the single joints, a 0.02, b 0.06, c 0.04, d 0.02, e 0.02, f 0.06; breadth (in the third joint) 0.11.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 648. Eusyringium,[[265]] Haeckel, 1881, Prodromus, p. 437.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, and prolonged into a terminal cylindrical tube. Cephalis with a solid horn.

The genus Eusyringium differs from the preceding closely allied genus Eucyrtidium in the peculiar formation of the last shell-joint, representing a narrow, cylindrical, fenestrated tube. It exhibits, therefore, to the latter the same relation as Theosyringium bears to Theocorys.

Subgenus 1. Eusyringartus, Haeckel.

Definition.—Shell with three strictures and four joints; the third joint is the largest, inflated, and much broader than the three others.

1. Eusyringium conosiphon, n. sp. (Pl. [78], fig. 10).

Shell with four joints, very thick-walled, rough. Cephalis hemispherical, with a very stout, smooth, three-sided pyramidal horn of the same length and breadth. Thorax hemispherical. Third joint subspherical, three times as long, and twice as broad as the thorax, and of the same length as the slender, inversely conical fourth joint. Pores in the three first joints subregular, circular, in the fourth joint irregular.

Dimensions.—Length of the shell (with four joints) 0.25. Length of the single joint a 0.02, b 0.03, c 0.1, d 0.1; breadth 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Eusyringium pachysiphon, n. sp. (Pl. [78], fig. 11).

Shell with four joints, very thick-walled, rough. Cephalis conical, with a thick, dimpled, conical horn of the same length. Thorax hemispherical. Third joint inflated, subspherical, and fourth joint slender, inversely conical, as in the similar preceding species. Differs from the latter mainly in the form of the cephalic horn, and the cylindrical tube of the last joint. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.3. Length of the single joints, a 0.03, b 0.03, c 0.12, d 0.12; breadth 0.15.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Eusyringium macrosiphon, n. sp. (Pl. [78], fig. 12).

Shell with four joints, thick-walled, rough. Cephalis subspherical with a large, dimpled, conical horn of twice the length. The three following joints nearly of the same shape as in the two similar preceding species. It differs from these in the smaller size, the larger cephalic horn, and the longer tube of the fourth joint, which is twice as long as the subspherical third joint (in the figure the lower half is broken off). Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.3. Length of the single joints, a 0.03, b 0.03, c 0.08, d 0.16; breadth 0.09.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Eusyringium leptosiphon, n. sp.

Shell with four joints, thin-walled, smooth. Cephalis subspherical, with a large, dimpled, slender, conical horn of three times the length. Thorax hemispherical. Third joint ovate, four times as long as the thorax, and of the same length as the thin, cylindrical tube of the fourth joint. Differs from the three preceding species in the more slender form and the thinness of the tube. Pores irregular, roundish.

Dimensions.—Length of the shell (with four joints) 0.33. Length of the single joints, a 0.02, b 0.03, c 0.13, d 0.15; breadth 0.1.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

5. Eusyringium sipho, Haeckel.

Eucyrtidium sipho, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 2.

Shell with four joints, thick-walled, smooth. Cephalis subspherical, hyaline, without pores, with a thick, conical horn of twice the length. Thorax hemispherical. Third joint ovate, four times as long as the thorax, and of the same length as the thin, cylindrical fourth joint. Pores subregular, circular, in the fourth joint twice as broad as in the third, and three times as broad as in the second joint.

Dimensions.—Length of the shell (with four joints) 0.22. Length of the single joints, a 0.02, b 0.02, c 0.09, d 0.09; breadth 0.08.

Habitat.—Fossil in Barbados.

6. Eusyringium fistuligerum, Haeckel.

Eucyrtidium fistuligerum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf ix. fig. 3.

Shell with four joints, thin-walled, smooth. Cephalis subspherical, with numerous very small pores, and a stout, pyramidal horn of the same length. Thorax hemispherical. Third joint subspherical, four times as long as the thorax, and of the same length as the slender, inversely conical or cylindrical, fourth joint. Pores irregular, roundish or circular, in the fourth joint twice as broad as in the two preceding joints.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.02, c 0.08, d 0.08; breadth 0.09.

Habitat.—Fossil in Barbados.

Subgenus 2. Eusyringoma, Haeckel.

Definition.—Shell with four or more strictures, and five or more joints; the last joint is strongly constricted, and forms a narrow cylindrical tube.

7. Eusyringium lagenoides, Haeckel.

Eucyrtidium lagenoides, Stöhr, 1880, Palæontogr., vol. xxvi. p. 104, Taf. iv. fig. 8.

Shell with five joints, and four sharp strictures, nearly spindle-shaped. The third joint is twice as long as the second and the fourth. Cephalis small, cap-shaped, with a thin conical horn of the same length. The fifth joint is in Stöhr's figure broken off, but well conserved in a specimen from Caltanisetta, and represents a slender cylindrical tube, with few pores, half as long as the shell. Pores small, subregular, circular, quincuncial.

Dimensions.—Length of the shell (with five joints) 0.24, breadth 0.08; length of the third joint 0.06, of the second and the fourth 0.03, of the fifth 0.1; breadth of the basal tube 0.027.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).

8. Eusyringium rhaphanus, Haeckel.

Eucyrtidium rhaphanus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 106, Taf. iv. fig. 12.

Shell with six or seven joints of very different lengths, in the upper half campanulate, in the lower cylindrical. The second and the two last joints are the longest. Cephalis small, subspherical, with a short conical horn. The last joint is a narrow cylindrical tube of variable length, scarcely one-fourth as broad as the preceding joints. Pores in the upper joints regular, circular, in the lower irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.1; length of the second and last joints 0.03 to 0.04; breadth of the basal tube 0.025.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte).

9. Eusyringium siphonostoma, n. sp. (Pl. [80], fig. 14).

Shell with eight joints, in the upper half slender, conical, in the lower half cylindrical. The single joints are separated by seven internal annular septa. The third and the seventh joints are the largest, twice as long as the three intercalated joints. Cephalis small, cap-shaped, with a conical horn of twice the length. The last joint (broken off in the specimen figured) is a narrow cylindrical tube, one-third as long and one-third as broad as the shell. Pores regular, circular, quincuncial.

Dimensions.—Length of the shell (with eight joints) 0.24, breadth 0.08; length of the single joints 0.02 to 0.04; breadth of the basal tube 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

10. Eusyringium cannostoma, n. sp. (Pl. [80], fig. 13).

Shell with nine or ten joints, slender ovate. The single joints are separated by eight or nine internal annular septa. The third joint is the longest, about twice or three times as long as each following joint. Cephalis hemispherical, with a curved, conical horn of the same length. The last joint is a narrow, cylindrical tube, about as long as the third joint, but only one-fourth as broad. Pores small, regular, circular, quincuncially disposed, and hexagonally framed.

Dimensions.—Length of the shell (with ten joints) 0.22, breadth 0.08; length of the third joint 0.04, of the other joints 0.01 to 0.02, of the basal tube 0.04; breadth of the latter 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 649. Siphocampe,[[266]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis with an oblique, open, apical tube.

The genus Siphocampe differs from the closely allied genera Lithocampe and Eucyrtidium in a very remarkable character, viz., the development of a hollow cylindrical tube on the cephalis. This probably serves for the emission of a bunch of pseudopodia. It has the same position and the same oblique direction on the cephalis as the solid apical horn of Eucyrtidium.

Subgenus 1. Siphocampula, Haeckel.

Definition.—All joints of the shell (excepting the first) are nearly equal in length.

1. Siphocampe tubulosa, n. sp. (Pl. [79], fig. 13).

Shell slender nearly spindle-shaped, with eight deep transverse strictures, and elegant longitudinal ribs. Nine joints slightly different in length and shape. Cephalis flat, cap-shaped, with three or four transverse rows of small pores, and a cylindrical, oblique tubule of twice the length. Each successive joint with a single transverse row of regular, circular pores at its lower edge, separated by divergent, longitudinal ribs. Last joint shorter, with a hyaline annular peristome of the same length. Mouth half as broad as the middle part of the shell.

Dimensions.—Length of the shell (with nine joints) 0.24; length of each joint (on an average) 0.02 to 0.03; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Siphocampe annulosa, n. sp. (Pl. [79], fig. 10).

Shell slender, subcylindrical, with nine slight transverse strictures, and interrupted longitudinal ribs. Ten joints nearly equal in length and shape, excepting the two first, which together form a hemispherical cephalothorax, with six to eight transverse rows of pores. Tubule of the cephalis short and wide, truncate, conical. Each of the eight abdominal joints with a single transverse row of small pores. Mouth constricted, without tubulose peristome, half as broad as the shell.

Dimensions.—Length of the shell (with ten joints) 0.18; length of each joint (on an average) 0.02, breadth 0.07.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Siphocampe caminosa, n. sp. (Pl. [79], fig. 12).

Shell slender, subcylindrical, with six deep transverse strictures. Seven joints nearly equal in length and breadth. Cephalis hemispherical, with an oblique, cylindrical tubule of twice the length (in the figure the greater part is broken away). Small circular pores in transverse rows and in variable number; usually three rows in the first and the last joint, five rows in the fourth joint, four rows in each of the other joints. Mouth constricted, with a short tubulose peristome, only one-third as broad as the shell.

Dimensions.—Length of the shell (with seven joints) 0.18; length of each joint (on an average) 0.025, breadth 0.055.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Siphocampe erucosa, n. sp. (Pl. [79], fig. 11).

Shell slender, nearly spindle-shaped, with five slight transverse strictures. Six joints nearly equal in length. The two first joints are united, and form together a hemispherical cephalothorax, with a short, oblique, cylindrical tubule. Pores regular, circular, double-contoured, in regular, transverse rows; two rows in the first and the last joints, four rows in each of the four middle joints. Mouth constricted, without peristome, only one-third as broad as the shell.

Dimensions.—Length of the shell (with six joints) 0.14; length of each joint (on an average) 0.02, breadth 0.07.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Subgenus 2. Siphocampium, Haeckel, 1881, Prodromus, p. 437.

Definition.—The joints of the shell are very different in length.

5. Siphocampe quadrantalis, n. sp.

Shell nearly spindle-shaped, with three deep strictures. Four joints of very different lengths. Cephalis subspherical with an oblique cylindrical tubule of twice the length, and with few small pores. Thorax ovate, half as long as the shell, with twelve transverse rows of small pores. Abdomen with two short joints, each of which has two transverse rows of pores. Mouth constricted, one-third as broad as the thorax.

Dimensions.—Length of the shell (with four joints) 0.18; length of the thorax 0.1, breadth 0.08.

Habitat.—Western Tropical Pacific; North Coast of New Guinea, Station 220, depth 1100 fathoms.

6. Siphocampe spiralis, n. sp. (Pl. [79], fig. 14).

Shell nearly spindle-shaped, with eight slight strictures. Nine joints of very different lengths. Cephalis subspherical, with an oblique cylindrical tubule of the same length, and numerous small pores. Thorax conical, one-fourth as long as the shell, with eight transverse rows of small pores. Abdomen with numerous prominent, spirally convoluted ribs, and spiral rows of pores between them. The first abdominal joint is from two to three times as long as each of the six following joints. Abdominal pores larger, roundish, disposed in eleven transverse rows. Four rows in the first abdominal joint, one row in each of the five following, and two rows in the last joint. Mouth slightly constricted, two-thirds as broad as the shell.

Dimensions.—Length of the shell (with nine joints) 0.17, cephalis 0.02, thorax 0.04, abdomen 0.11; breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados.

Genus 650. Lithocampe,[[267]] Ehrenberg, 1838, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 128 (sensu emendato).

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis without horn and tube.

The genus Lithocampe is the oldest of all "Polycystina," being founded by Ehrenberg in 1838 upon Lithocampe radicula. Afterwards numerous other species, which belong to very different genera, were described by him. In 1862 I attempted to give a more strict definition of this genus in my Monograph (p. 312 to 315), and separated it from the closely allied and often confounded Eucyrtidium by the absence of a cephalic horn. The great number of species afterwards discovered leads to the stricter definition given above.

Subgenus 1. Lithocampula, Haeckel.

Definition.—All joints of the shell (except often the first) are equal or nearly equal in length.

1. Lithocampe eupora, Haeckel.

Eucyrtidium euporum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. iv. fig. 30.

Shell smooth, ovate or subconical, with three deep strictures. Four joints equal in length, gradually increasing in breadth, each with three transverse rows of regular, circular, hexagonally-framed pores; the fourth joint is the broadest. Mouth little constricted, of the same breadth as the third joint.

Dimensions.—Length of the shell (with four joints) 0.08; length of each joint 0.02, greatest breadth 0.06.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; North Atlantic, depth 3600 fathoms (Morse).

2. Lithocampe platycephala, Haeckel.

Eucyrtidium platycephalum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, pp. 145, 293, Taf. iii. fig. 16.

Shell smooth, subconical or slenderly ovate, with three slight strictures. Four joints equal in length, slightly increasing in breadth towards the mouth. The hemispherical cephalis with longitudinal ribs and irregular pores, each of the three other joints with four transverse rows of regular, circular pores. Mouth strongly constricted, half as broad as the third and fourth joints.

Dimensions.—Length of the shell (with four joints) 0.12; length of each joint 0.03, greatest breadth 0.06.

Habitat.—North Atlantic, depth 3600 fathoms (Morse).

3. Lithocampe nereidum, Haeckel.

Lithocampe nereidum, Haeckel, 1862, Monogr. d. Radiol., p. 319.

Eucyrtidium nereidum, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 242; Mikrogeol., Taf. xxxv. B, b, fig. 22.

Shell smooth, slenderly ovate, with four deep strictures. Five joints equal in length, the fourth being the broadest. Each joint with three transverse rows of small, regular, circular pores (sometimes in the fourth joint there are four rows). Mouth constricted, half as broad as the fourth joint. (In Ehrenberg's figure all five joints are delineated, but the greater part of the hemispherical cephalis is broken off.)

Dimensions.—Length of the shell (with five joints) 0.1, of each joint 0.02; breadth of the fourth joint 0.05.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

4. Lithocampe radicula, Ehrenberg.

Lithocampe radicula, Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 130, Taf. iv. fig. 11.; Mikrogeol., 1854, Taf. xxii. fig. 23a.

Shell smooth, spindle-shaped, with five sharp strictures. Six joints equal in length, each with four transverse rows of regular, circular, double-edged pores. The third and fourth joints are the broadest, and equal. The constricted mouth is not broader than the hemispherical cephalis, scarcely one-fourth as broad as the third and the fourth joints. This remarkable species is the oldest known skeleton of a Radiolarian, a figure of it being given in 1838, loc. cit. (compare my Monograph, 1862, p. 3, 4, 331). But this figure of Ehrenberg is not quite accurate, and differs from other figures of the same species, which he afterwards (1854) published in his Mikrogeologie (loc. cit.). The best of these is fig. 23a in pl. xxii., and is identical with the typical form (common in Barbados), and according to this I have here framed my description. The sixth joint possesses a distinct (though small) terminal mouth; when this becomes closed, the species passes over into Stichocapsa radicula.

Dimensions.—Length of the shell (with six joints) 0.18, length of each joint (on an average) 0.03; breadth of the third and fourth joints 0.08, of the second and fifth 0.06, of the terminal mouth and the cephalis 0.03.

Habitat.—Fossil in Tertiary rocks of Barbados.

5. Lithocampe ventricosa, Haeckel.

Dictyomitra ventricosa, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iii. fig. 25.

Shell ovate, with six slight strictures. Seven joints nearly equal in length, each with four (or sometimes three or five) transverse rows of small, regular, circular pores, in the last joint the pores are larger. The fourth and fifth joints are the broadest, and are twice as broad as the constricted mouth.

Dimensions.—Length of the shell (with seven joints) 0.13 to 0.14; length of each joint 0.017 to 0.02, greatest breadth 0.083, mouth 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

6. Lithocampe fusiformis, n. sp.

Shell smooth, spindle-shaped, decreasing uniformly towards the two blunt poles, with eight or nine sharp strictures, and nine or ten joints of equal lengths, each with four transverse rows of regular, hexagonal pores. The fourth and fifth joints are the broadest. The constricted mouth is twice as broad as the hemispherical cephalis, half as broad as the fourth joint.

Dimensions. —Length of the shell (with ten joints) 0.2, of each joint 0.02; breadth of the fourth joint 0.06, mouth 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 2. Lithocampium, Haeckel, 1881, Prodromus, p. 437.

Definition.—The joints of the shell are very different in length.

7. Lithocampe ovata, n. sp. (Pl. [77], fig. 1).

Shell smooth, urceolate or ovate, with three sharp strictures. Four joints of different lengths, having the proportion 1 : 2 : 2 : 6. The fourth joint is inflated and the broadest. The mouth is constricted, short, tubular, of the same breadth as the hemispherical cephalis. Pores small, circular, in regular transverse rows; four rows in the first, four in the second, two in the third, and five in the fourth joint. The middle stricture is crossed by longitudinal ribs.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.01, b 0.02, c 0.02, d 0.06; greatest breadth 0.055.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Lithocampe aquilonaris, Haeckel.

Lithocampe aquilonaris, Haeckel, 1862, Monogr. d. Radiol., p. 317.

Eucyrtidium aquilonare, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 4, pl. i. fig. 9.

Shell smooth, subconical, with three distinct strictures. Four joints of different lengths, having the proportion 3 : 1 : 3 : 4. The fourth joint is the broadest, suddenly constricted, with a short tubular mouth of half the breadth. Pores subregular, circular, in transverse rows; three rows in the first joint, two in the second, four in the third, and three in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.03, b 0.01, c 0.03, d 0.04; breadth 0.06.

Habitat.—North Pacific, Kamtschatka (Bailey), Station 241, depth 2300 fathoms.

9. Lithocampe quadrarticulata, Haeckel.

Lithocampe quadrarticulata, Haeckel, 1862, Monogr. d. Radiol., p. 319.

Eucyrtidium quadrarticulatum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 299.

Shell smooth, spindle-shaped, with three deep strictures. Four joints of different lengths = 1 : 3 : 4 : 3. The third joint is the broadest, being twice as broad as the constricted mouth of the fourth joint. Pores small, regular, circular, in transverse rows; two being in the first, three in the second, four in the third, three in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.03, c 0.04, d 0.025; greatest breadth 0.05.

Habitat.—North Atlantic (Greenland, depth 1600 fathoms, Ehrenberg), Station 64, surface.

10. Lithocampe multiseriata, Haeckel.

Eucyrtidium multiseriatum, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, page 293, Taf. vii. fig. 9.

Shell smooth, spindle-shaped, or slenderly ovate, with three sharp strictures. Four joints of different lengths = 3 : 4 : 5 : 10. The third and fourth joints nearly equal in breadth, and twice as broad as the hemispherical cephalis. The truncate mouth is slightly constricted. Pores very small and numerous, in regular transverse rows. Three or four rows in the first, five or six in the second, seven or eight in the third, and fifteen to twenty in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.02, c 0.025, d 0.05; breadth 0.045.

Habitat.—Tropical Pacific (Philippine Sea, Ehrenberg), Stations 206, 224, 266, in various depths.

11. Lithocampe diploconus, n. sp. (Pl. [77], fig. 3).

Shell rough, doubly conical, with three distinct strictures. Four joints of different lengths = 2 : 5 : 5 : 8. The third joint is the broadest. The three first joints form together a broad cone, and the fourth an inverse truncate cone; the latter is distinguished by convergent longitudinal ribs. Pores regular, circular, alternating with the ribs in the fourth joint. Truncate mouth hyaline, half as broad as the third joint.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.05, c 0.05, d 0.08; breadth (in the middle part) 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

12. Lithocampe diaphana, Haeckel.

Eucyrtidium diaphanum, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 309.

Shell smooth, hyaline, spindle-shaped, decreasing uniformly towards both poles, with three distinct strictures. Four joints of different lengths; the second and third equal in breadth, twice as broad and three times as long as the first and the fourth. Pores very small and scarce, in transverse interrupted rows, commonly two rows in the first, two or three in the second, three or four in the third, and only one in the last joint. Mouth constricted, two-thirds as broad as the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.13. Length of the single joints, a 0.015, b 0.05, c 0.05, d 0.015; breadth (in the middle part) 0.06, mouth 0.02.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

13. Lithocampe hispida, Haeckel.

Lithocampe hispida, Haeckel, 1862, Monogr. d. Radiol., p. 318.

Eucyrtidium hispidum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 298; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 291, Taf. ii. fig. 19.

Shell thorny, slenderly ovate, or nearly spindle-shaped, with four sharp strictures. Five joints of different lengths = 3 : 3 : 4 : 6 : 4. The fourth joint is the broadest, and nearly twice as broad as the constricted mouth. Pores small, circular, separated by longitudinal, spiny ribs, regularly disposed in transverse rows; three rows in the first and second, four rows in the third and fifth, six rows in the fourth joint.

Dimensions.—Length of the shell (with five joints) 0.1. Length of the single joints, a 0.015, b 0.015, c 0.02, d 0.03, e 0.02; greatest breadth 0.05.

Habitat.—Arctic Ocean (in different depths), Ehrenberg.

14. Lithocampe tumidula, Haeckel.

Lithocampe tumidula, Haeckel, 1862, Monogr. d. Radiol., p. 318.

Eucyrtidium tumidulum, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 5, pl. i. fig. 11.

Eucyrtidium tumidulum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. ii. fig. 12.

? Eucyrtidium increscens, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 299.

? Lithocampe increscens, Haeckel, 1862, Monogr. d. Radiol., p. 318.

Shell smooth, nearly spindle-shaped, with four sharp strictures, very similar to the preceding in size and form. It differs in the smooth surface, the absence of longitudinal ribs, and the unequal size of the pores, which form four transverse series in each joint, and are much larger in the broadest (fourth) joint. Proportion of the five joints = 2 : 2 : 3 : 5 : 4.

Dimensions.—Length of the shell (with five joints) 0.1. Length of the single joints, a 0.012, b 0.012, c 0.02, d 0.03, e 0.025; greatest breadth 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, in different depths.

15. Lithocampe heteropora, Haeckel.

Lithocampe heteropora, Haeckel, 1862, Monogr. d. Radiol., p. 317.

Eucyrtidium heteroporum, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 242.

Shell smooth, subconical, obtuse, with four distinct strictures. Five joints of different lengths = 2 : 4 : 3 : 3 : 2. The fourth joint is the broadest. Mouth slightly constricted. Pores regular, circular, in the second joint much larger than in the four others, disposed in transverse series; two rows in the first and fifth, three rows in the second, four rows in the third and fourth joints.

Dimensions.—Length of the shell (with five joints) 0.14. Length of the single joints, a 0.02, b 0.04, c 0.03, d 0.03, e 0.02; greatest breadth 0.07.

Habitat.—North Atlantic (depth 2000 fathoms, Ehrenberg), Canary Islands, surface, Haeckel.

16. Lithocampe meta, Stöhr.

Lithocampe meta, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, Taf. iv. fig. 4.

Shell rough, subconical, obtuse, with four slight strictures. Five joints of different lengths = 2 : 4 : 5 : 4 : 2. The fourth joint is the broadest, and three times as broad as the constricted mouth. Pores, small, regular, circular, quincuncially disposed, equal in size; two transverse rows in the first and fifth, five rows in the second and fourth, six rows in the third joint.

Dimensions.—Length of the shell (with five joints) 0.14. Length of the single joints, a 0.017, b 0.033, c 0.04, d 0.033, e 0.017; greatest breadth 0.083.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr), Caltanisetta (Haeckel).

17. Lithocampe urceolata, n. sp. (Pl. [77], fig. 2).

Shell rough, wide, urceolate, without external strictures, but with four internal septal rings (not visible in the figure), each of which contains an internal circle of horizontal pores. Five joints of different lengths = 2 : 3 : 6 : 4 : 2. The third joint is the broadest, and three times as broad as the constricted mouth. Pores of very different sizes, irregular, roundish, with prominent polygonal frames. A very remarkable species.

Dimensions.—Length of the shell (with five joints) 0.17. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.04, e 0.02; greatest breadth 0.13.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

18. Lithocampe clava, Ehrenberg.

Lithocampe clava, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iv. fig. 2.

Shell smooth, club-shaped, or slenderly ovate, with five internal septal rings. Six joints of very different lengths = 5 : 2 : 3 : 4 : 5 : 18. The sixth joint is the broadest, and as long as the five others together. Pores small, circular, in the basal half of the last joint irregular and larger. Constricted mouth as broad as the subspherical, hyaline cephalis.

Dimensions.—Length of the shell (with six joints) 0.15. Length of the single joints, a 0.02, b 0.011, c 0.013, d 0.016, e 0.02, f 0.07.

Habitat.—Fossil in Barbados.

19. Lithocampe hexacola, n. sp. (Pl. [79], fig. 7).

Shell smooth, nearly spindle-shaped, without external strictures, but with five internal septal rings. Six joints of different lengths = 4 : 8 : 5 : 5 : 5 : 10. The fourth joint is the broadest, and four times as broad as the constricted mouth. Pores subregular hexagonal, or irregular polygonal, with thin bars.

Dimensions.—Length of the shell (with six joints) 0.18, greatest breadth 0.09. Length of the six joints, a 0.02, b 0.04, c, d, and e each 0.025, f 0.05.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

20. Lithocampe heptacola, n. sp. (Pl. [79], fig. 8).

Shell smooth, subcylindrical, constricted at both poles, with six distinct strictures. Seven joints of different lengths, the five abdominal joints nearly equal, each half as long as the hemispherical, vaulted thorax, and twice as long as the subspherical, small cephalis. Mouth constricted, with a short, tubular, hyaline peristome (like an eighth joint without pores), about one-third as broad as each of the four middle joints. Pores subregular hexagonal, or irregular polygonal, with thin bars.

Dimensions.—Length of the shell (with seven joints) 0.24, greatest breadth 0.09. Length of the cephalis 0.02, thorax 0.06, each of the four following joints 0.03, of the last joint 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

21. Lithocampe octocola, n. sp. (Pl. [79], fig. 6).

Shell smooth, subcylindrical, thick-walled, constricted at both poles, without distinct, external strictures, but with seven internal septal rings. Eight joints of different lengths; four joints (the second to the fifth) being about twice as long as the four others (the first and the three last). The constricted mouth only one-third as broad as the four middle joints. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with eight joints) 0.19, breadth 0.09. Length of the second to the fifth joints, each 0.03; length of the four other joints, each about 0.016.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

22. Lithocampe polycola, n. sp.

Shell smooth, subcylindrical, constricted at both poles, with twelve to fifteen distinct strictures. Fourteen to sixteen joints of different lengths. Cephalis flat, cap-shaped, hyaline, without pores. Thorax nearly hemispherical, with three transverse rows of small circular pores. Each following joint (each abdominal joint) only with a single row of small pores. The constricted mouth of the last joint only one-third as broad as the middle part of the shell. (Very similar to Lithomitra eruca, Pl. [79], fig. 3.)

Dimensions.—Length of the shell (with sixteen joints) 0.3, breadth 0.08. Length of the cephalis 0.02, thorax 0.06, each of the following joints 0.015, last joint 0.025.

Habitat.—Tropical Pacific, Station 224, depth 1850 fathoms.

Genus 651. Spirocyrtis,[[268]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with spirally-arranged constrictions on the shell. Cephalis with a horn.

The genus Spirocyrtis and the following closely allied genus Spirocampe differ from the other Stichocorida (and also from nearly all Cyrtoidea) in a very remarkable character. The annular constrictions of the multiarticulate shell and the corresponding internal annular septa are here not separated, and do not lie in parallel, transverse planes (as usually happens), but they are all or partly connected in the form of an ascending spiral, so that the joints are not perfectly separated. An irregularity or asymmetry of growth on the different sides of the shell is probably the cause of this strange, spiral structure.

Subgenus 1. Spirocyrtidium, Haeckel.

Definition.—Shell conical, gradually dilating towards the wide open terminal mouth.

1. Spirocyrtis scalaris, n. sp. (Pl. [76], fig. 14).

Shell conical, gradually dilating towards the wide open mouth, with ten to twelve spiral convolutions, which correspond to the same number of short and broad chambers or joints, gradually increasing in breadth; all joints form together a spirally winding staircase. The length or height of the single joints or stairs is about equal, and each bears four or five transverse rows of small, square pores. Cephalis flat, cap-shaped, with two or three short divergent horns.

Dimensions.—Length of the shell (with ten joints or turnings) 0.16, length of each joint (on an average) 0.016; breadth of the third joint 0.04, of the fifth joint 0.07, of the tenth joint 0.1.

Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

2. Spirocyrtis cornutella, n. sp. (Pl. [76], fig. 13).

Shell conical, gradually dilating towards the wide mouth, similar to the preceding, but differing in the curved axis, and the broader and shorter joints, each of which bears only two or three transverse rows of square pores. The turnings of the staircase are not so sharp, nor so distinct, as in the preceding species. Cephalis with a single short horn.

Dimensions.—Length of the shell (with eight joints) 0.1; breadth of the fourth joint 0.05, of the eighth joint 0.08.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Subgenus 2. Spirocyrtoma, Haeckel.

Definition.—Shell ovate, or nearly spindle-shaped, more or less tapering towards the narrower, somewhat constricted mouth.

3. Spirocyrtis holospira, n. sp. (Pl. [76], fig. 16).

Shell subovate, twice as long as broad, without external strictures, but with an internal regularly descending spiral septum, which separates seven to nine broad joints of nearly equal lengths; the first and second joints together are conical, and about as long as each of the following joints. Cephalis small, hemispherical, with a thick pyramidal horn of the same length. The fifth joint is the broadest, the truncate mouth is slightly constricted (in the specimen figured it is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1; length of each joint, about 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Spirocyrtis hemispira, n. sp.

Shell slender, nearly spindle-shaped, three times as long as broad, without external strictures, but with ten to eleven internal septa. The five or six upper of these are perfectly separate, complete parallel rings; the five or six lower are spirally connected. The eleven or twelve joints gradually taper in length and breadth, from the broadest middle towards the two constricted ends of the shell. The middle (fifth or sixth) joint is the broadest, and is three to four times as broad as the constricted mouth. Cephalis small, hemispherical, with a conical horn of the same length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with twelve joints) 0.25, breadth 0.09; length of the middle joint 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Spirocyrtis merospira, n. sp. (Pl. [76], fig. 15).

Shell ovate, with six to eight slight strictures, twice as long as broad. The three or four upper joints are perfectly separated by annular septa, the three or four lower joints connected by an internal spiral septum. The spiral line is often more or less irregular or interrupted (as is also the case in the specimen figured). Mouth rather wide. Pores small, subregular, circular. A rather variable species.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

6. Spirocyrtis diplospira, n. sp. (Pl. [76], fig. 17).

Shell slender, ovate, with seven to eight slight strictures. All eight or nine joints are connected by an internal double spiral septum, the first spiral beginning from the ventral side, the second from the dorsal side of the collar stricture. Length and breadth of the single joints rather variable and irregular; the broadest joint is commonly the fifth. Mouth more or less constricted. Pores subregular, circular. This remarkable species differs from all other Cyrtoidea by the double spiral septum of the joints.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 652. Spirocampe,[[269]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with spirally arranged constrictions on the shell. Cephalis without horn.

The genus Spirocampe has the same peculiar spiral structure of the shell as the preceding Spirocyrtis, and differs from it only in the absence of a cephalic horn. It exhibits, therefore, the same relation to the latter as the similar Lithocampe bears to Eucyrtidium.

1. Spirocampe callispira, n. sp. (Pl. [76], fig. 11).

Shell ovate, smooth, with six joints, connected in the form of a complete winding staircase. All the windings are nearly at equal distances; each bears one row of large roundish pores, enclosed by two rows of smaller pores. Cephalis hemispherical, of about the same breadth as the constricted, short tubular mouth.

Dimensions.—Length of the shell (with six joints) 0.15, breadth 0.09; mouth 0.03 diameter.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

2. Spirocampe allospira, n. sp. (Pl. [76], fig. 12).

Shell subcylindrical, or nearly spindle-shaped, smooth, very thick-walled, with eight joints alternately longer and shorter, and connected in the form of an irregular spiral. The distance between the windings is very variable. Pores small, regular, circular. Cephalis hemispherical, of about the same size as the short tubular mouth.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.08; mouth 0.03 diameter.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

3. Spirocampe polyspira, n. sp.

Shell cylindrical, rough, with twelve joints nearly equal in length, connected in the form of a regular, complete spiral. All windings are at the same distance. Pores regular, circular, three rows on each turning. Cephalis flat, cap-shaped, half as broad as the slightly constricted, not tubular mouth.

Dimensions.—Length of the shell (with twelve joints) 0.24, breadth 0.07; mouth 0.05 diameter.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily 2. Stichocapsida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Lithocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida eradiata clausa).

Genus 653. Cyrtocapsa,[[270]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) with an apical horn on the cephalis, without basal terminal spine.

The genus Cyrtocapsa and the two following genera represent together the small subfamily of Stichocapsida, or of those Cyrtoidea in which the many-jointed shell bears no radial appendages, and the terminal mouth is closed by a lattice-plate. They have been derived from the Stichocorida by development of such a closing plate. Cyrtocapsa bears an apical horn on the cephalis, and may be derived therefore directly from Eucyrtidium.

Subgenus 1. Cyrtocapsella, Haeckel.

Definition.—Shell with three annular strictures (or internal septa) and four distinct joints.

1. Cyrtocapsa tetrapera, n. sp. (Pl. [78], fig. 5).

Shell rough, pear-shaped, with three deep strictures. The three first joints are of equal lengths, and each half as long as the hemispherical fourth joint. Cephalis subspherical, with an oblique conical horn of the same length. The third joint is the broadest, three times as broad as long. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.09; length of each of the three first joints 0.03, of the last 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Cyrtocapsa compacta, n. sp. (Pl. [77], fig. 8).

Eucyrtidium compactum, Haeckel, 1878, Atlas, loc. cit.

Shell rough, pear-shaped, with three slight strictures. The hemispherical cephalis bears a thick pyramidal spine of the same length, and is half as long as the second and the third joints, one-third as long as the hemispherical fourth joint. The third joint is the broadest, three times as broad as long. Pores subregular, circular. In the centre of the basal pole is one larger pore, the remnant of the constricted mouth of Eucyrtidium.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.04, d 0.06.

Habitat.—Western Tropical Pacific, Station 206, depth 2100 fathoms.

3. Cyrtocapsa inflata, n. sp.

Shell spiny, pear-shaped, with three deep strictures. The inflated third joint is twice as long as the second and fourth joints, and three times as long as the hemispherical cephalis, which bears a large conical horn of three times the length. Fourth joint flat, vaulted, inversely cap-shaped. The third joint is the broadest, being twice as broad as long. Pores regular, circular, double-contoured.

Dimensions.—Length of the shell 0.14, breadth 0.11. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.03.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Cyrtocapsa pyrum, n. sp. (Pl. [78], fig. 8).

Shell thorny, pear-shaped, without external strictures, but with three internal annular septa. Length of the four joints = 2 : 5 : 6 : 7. The fourth joint is the broadest, being about twice as broad as long, and hemispherical. The small subspherical cephalis bears a stout conical horn of the same length. Pores large, regular, circular.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.12. Length of the single joints, a 0.02, b 0.05, c 0.06, d 0.07.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Cyrtocapsa cornuta, n. sp. (Pl. [78], fig. 9).

Shell rough, very thick-walled, nearly pear-shaped, with three annular strictures; the second of which is very sharp, the first and third slight. Length of the four joints = 3 : 4 : 5 : 6. The third joint is the broadest, being about twice as broad as long; the fourth joint is hemispherical. Cephalis subspherical, with a large, conical, curved horn of twice the length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.12. Length of the single joints, a 0.03, b 0.04, c 0.05, d 0.06.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Cyrtocapsa diploconus, n. sp. (Pl. [78], fig. 6).

Shell rough, doubly conical, with three annular septa. Length of the four joints = 3 : 4 : 4 : 8. The third joint is the broadest, two and a half times as broad as long; the fourth is inversely conical, acute. Cephalis hemispherical, with a pyramidal horn of the same length. Pores irregular, roundish.

Dimensions.—Length of the shell (with four joints) 0.19, breadth 0.1. Length of the single joints, a 0.03, b 0.04, c 0.04, d 0.08.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

7. Cyrtocapsa fusulus, n. sp. (Pl. [78], fig. 7).

Shell smooth, spindle-shaped, with three distinct strictures. Length of the four joints = 1 : 1 : 4 : 3. The third joint is the broadest, somewhat longer than broad. The fourth joint is inversely conical. Cephalis hemispherical, with a coronal of large, ovate pores, and a pyramidal, sulcate, oblique horn of twice the length. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.07. Length of the single joints, a 0.02, b 0.02, c 0.08, d 0.06.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subgenus 2. Cyrtocapsoma, Haeckel.

Definition.—Shell with four or more annular septa, and five or more joints.

8. Cyrtocapsa incrassata, Haeckel.

Eucyrtidium incrassatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 9.

Shell rough, spindle-shaped, with four annular septa. Length of the five joints = 2 : 3 : 4 : 4 : 4. The third joint is the broadest, nearly three times as broad as long. The fourth joint is inversely conical, acute. Cephalis small, spherical, with two short, conical, divergent horns. Pores small, regular, circular.

Dimensions.—Length of the shell (with five joints) 0.17, breadth 0.11. Length of the single joints, a 0.015, b 0.035, c 0.04, d 0.04, e 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte.

9. Cyrtocapsa costata, n. sp.

Shell smooth, spindle-shaped, twice as long as broad, with numerous longitudinal ribs, and four annular septa. Length of the five joints = 1 : 4 : 3 : 2 : 8. The third joint is the broadest. Fourth joint inversely conical, acute. Cephalis small, hemispherical, with a small conical horn. Pores regular, circular.

Dimensions.—Length of the shell (with five joints) 0.18, breadth 0.09. Length of the single joints, a 0.01, b 0.04, c 0.03, d 0.02, e 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

10. Cyrtocapsa colatractus, n. sp.

Shell smooth, spindle-shaped, with eight internal annular septa (without external stricture). All nine joints are nearly equal in length, the first somewhat shorter, the last longer. The fourth joint is the broadest, four times as broad as long. Last joint inversely conical, blunt. Cephalis subspherical, with a conical horn of the same length. Pores small and numerous, regular, circular.

Dimensions.—Length of the shell (with nine joints) 0.22, breadth 0.1; length of the cephalis 0.015, of the last joint, 0.03, of each of the seven other joints, 0.022 to 0.028.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

11. Cyrtocapsa chrysalidium, n. sp. (Pl. [76], fig. 9).

Shell rough, nearly spindle-shaped, with seven distinct strictures. Length of the eight joints = 4 : 6 : 11 : 8 : 5 : 5 : 4 : 3. The third and fourth joints are the broadest. The last joint is small, inversely cap-shaped. Cephalis subspherical, with an oblique, dentate horn of the same length. Pores very numerous, subregular, circular.

Dimensions.—Length of the shell (with eight joints) 0.23, breadth 0.1. Length of the single joints, a 0.02, b 0.03, c 0.055, d 0.04, e 0.025, f 0.025, g 0.02, h 0.015.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 654. Stichocapsa,[[271]] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) without apical horn, and without basal spine.

The genus Stichocapsa differs from the preceding Cyrtocapsa in the absence of an apical horn, and bears therefore to it the same relation as Lithocampe does to Eucyrtidium. It may be derived either from Cyrtocapsa by loss of the horn, or from Eucyrtidium by closure of the terminal mouth.

1. Stichocapsa tetracola, n. sp. (Pl. [78], fig. 1).

Shell smooth, spindle-shaped, half as broad as long, with three slight strictures. Length of the four joints = 3 : 4 : 4 : 11. The fourth joint is the broadest, inversely conical, with acute basal pole. Pores subregularly square in the second and third joints, more irregular in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.02, c 0.02, d 0.055; breadth 0.055.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Stichocapsa quadrigata, n. sp. (Pl. [78], fig. 3).

Shell smooth, pear-shaped, half as broad as long, with three deep strictures. Length of the four joints = 3 : 8 : 8 : 5. The second joint is the broadest. The fourth joint is scarcely larger than the hemispherical cephalis, inversely conical, with blunt basal pole. Pores subregular, square, in transverse rows, in the second and third joints of equal size, in the fourth smaller.

Dimensions.—Length of the shell (with four joints) 0.12. Length of the single joints, a 0.015, b 0.04, e 0.04, d 0.025; breadth 0.06.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

3. Stichocapsa tricincta, n. sp. (Pl. [78], fig. 2).

Shell smooth, spindle-shaped, twice as long as broad, with three deep strictures. Length of the four joints = 2 : 5 : 5 : 10. The third joint is the broadest. Fourth joint inversely conical, with acute basal pole. Cephalis small, subconical. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the shell 0.11. Length of the single joints, a 0.01, b 0.025, e 0.025, d 0.05; breadth 0.055.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

4. Stichocapsa subglobosa, n. sp.

Shell thorny, broad, pear-shaped, nearly spherical, almost as broad as long, with three internal septal rings. Length of the four joints = 1 : 2 : 7 : 2. Cephalis small, subspherical. Thorax flat, conical. Third joint very large, inflated, about twice as broad as the second and fourth joints. The latter is flat, cap-shaped, with rounded basal pole. Pores regular, circular, hexagonally framed, in the third joint twice as broad as in the second and fourth joints.

Dimensions.—Length of the shell 0.24. Length of the single joints, a 0.02, b 0.04, c 0.14, d 0.04; breadth 0.2.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

5. Stichocapsa compressa, Haeckel.

Lithocampe compressa, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, Taf. iv. fig. 5.

Shell rough, broad, pear-shaped, almost as broad as long, with three internal septal rings. Length of the four joints = 1 : 2 : 3 : 2. Cephalis very small, spherical. Thorax conical. The third joint is the broadest, strongly inflated. The fourth joint (in the figure of Stöhr broken off) is in a well preserved specimen inversely hemispherical, with rounded basal pole. Pores very small, regular, circular.

Dimensions.—Length of the shell 0.1. Length of the single joints, a 0.013, b 0.027, c 0.04, d 0.022; breadth 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

6. Stichocapsa pyriformis, n. sp.

Shell rough, pear-shaped, about twice as long as broad, with three internal septal rings. Length of the four joints = 2 : 5 : 2 : 9. Cephalis small, spherical, hyaline. Thorax conical. Third joint very short and broad; the fourth joint is the broadest, half as long as the shell, with an inversely hemispherical basal pole. Pores subregular, circular, small and numerous, larger in the basal third.

Dimensions.—Length of the shell 0.18. Length of the single joints, a 0.02, b 0.05, c 0.02, d 0.09; breadth 0.1.

Habitat.—Fossil in Barbados.

7. Stichocapsa monstrosa, n. sp. (Pl. [78], fig. 4).

Shell tuberculate, twice as long as broad, irregular, horn-shaped or inversely conical, with curved axis, and with three internal septal rings. Length of the four joints = 2 : 7 : 3 : 4. Cephalis subspherical, with small, circular pores. The thorax is the broadest joint, half as long as the shell. The fourth joint is small, inversely conical, with a blunt, curved, basal pole. Pores irregular, roundish, partly double-contoured.

Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.02, b 0.07, c 0.03, d 0.04; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Stichocapsa pentacola, n. sp. (Pl. [76], fig. 1).

Shell smooth, slender, pear-shaped, twice as long as broad, with four sharp strictures. Length of the five joints = 1 : 1 : 1 : 2 : 3. The three first joints are nearly equal in length, but increase in breadth. The fifth joint is the broadest, nearly spherical, with rounded basal pole. Pores irregular, roundish.

Dimensions.—Length of the shell (with five joints) 0.13. Length of the single joints, a 0.017, b 0.017, c 0.017, d 0.028, e 0.05; breadth 0.07.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

9. Stichocapsa hexacola, n. sp. (Pl. [76], fig. 2).

Shell rough, slender, pear-shaped, twice as long as broad, with five internal septal rings. The five first joints are nearly equal in length. The sixth joint is the broadest, half as long as the shell, with a rounded, hemispherical basal pole. Pores small and numerous, subregular, circular, larger in the inflated basal third.

Dimensions.—Length of the shell (with six joints) 0.2. Length of each of the first five joints 0.02, of the sixth joint 0.1; breadth 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.

10. Stichocapsa compacta, n. sp. (Pl. [76], fig. 3).

Shell rough very thick-walled, slender, pear-shaped, twice as long as broad, without external stricture, but with eight internal septal rings. The eight first joints, gradually increasing in breadth, are nearly equal in length. The eighth joint is the broadest, and one-third as long as the shell, inversely hemispherical. Pores small, circular, in the last joint larger.

Dimensions.—Length of the shell (with nine joints) 0.25. Length of each of the eight first joints about 0.02, of the ninth joint 0.08; breadth 0.13.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

11. Stichocapsa radicula, Haeckel.

Lithocampe radicula, Ehrenberg, 1838 (partim); Mikrogeol., 1854, Taf. xxii. fig. 23b.?

Shell smooth, spindle-shaped, decreasing from the broader middle towards the two rounded poles, with four or five slight strictures. All five or six joints nearly equal in length, the middle (third and fourth) are the broadest. Pores subregular, circular. (To this species those forms of Lithocampe radicula, Ehrenberg, must be referred, in which the basal opening is perfectly closed by lattice-work. The other forms in which the basal mouth remains open, and which are connected with the former by transitional forms, constitute the true type of the genus Lithocampe (page 1503).

Dimensions.—Length of the shell (with six joints) 0.12 to 0.15, breadth 0.06 to 0.07.

Habitat.—Fossil in Barbados.

12. Stichocapsa subligata, Haeckel.

Lithocampe subligata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iv. fig. 1.

Shell rough, subcylindrical, irregular, with seven slight strictures. All eight joints of slightly different lengths, the third joint is the broadest; the seventh joint is much broader than the sixth and the eighth joints. The latter is inversely hemispherical. Cephalis very small, spherical. Pores regular, circular, very small and numerous.

Dimensions.—Length of the shell (with eight joints) 0.24; length of the single joints (on an average) 0.025 to 0.035, breadth 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte).

13. Stichocapsa paniscus, n. sp. (Pl. [76], fig. 4).

Shell smooth, cylindrical, with a blunt, conical cephalis, and a hemispherical last joint, without external strictures, but with seven or eight internal septa. Eight or nine joints nearly equal in length, the second and the last somewhat longer. Pores circular, of unequal sizes.

Dimensions.—Length of the shell (with seven joints) 0.16; length of each joint (on an average) 0.02 to 0.03, breadth 0.07.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

14. Stichocapsa cylindrica, n. sp.

Shell rough, cylindrical, four times as long as broad, with hemispherical cephalis and last joint, without external stricture, but with ten or eleven internal septa. All eleven or twelve joints are nearly equal in length, and are three times as broad as long. Only the flat cephalis is shorter, and the vaulted last joint longer than each of the nine or ten other joints. Pores regular, circular.

Dimensions.—Length of the shell (with twelve joints) 0.24; length of each joint (on an average) 0.02, breadth 0.06.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

Genus 655. Artocapsa,[[272]] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) with an apical horn on the cephalis, and a basal terminal spine on the last joint.

The genus Artocapsa differs from Cyrtocapsa, its ancestral form, by the development of a vertical terminal spine, or a bunch of spines, on the base of the last joint, and bears therefore to it the same relation as Rhopalatractus does to Rhopalocanium.

1. Artocapsa fusiformis, n. sp. (Pl. [76], fig. 5).

Shell spindle-shaped, rough, with five slight strictures, decreasing uniformly from the broader middle towards both poles, with a strong, pyramidal, terminal spine at each pole. Length of the six joints = 2 : 5 : 3 : 3 : 2 : 5. Cephalis hemispherical, hyaline, without pores, its horn half as large as the basal spine. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the single joints, a 0.02, b 0.05, c 0.03, d 0.03, e 0.02, f 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Artocapsa spinosa, n. sp. (Pl. [76], fig. 10).

Shell spindle-shaped, spiny, with five distinct strictures. Length of the six joints = 2 : 3 : 2 : 5 : 4 : 4. The fourth joint is the broadest, and much larger than the five other joints. The first and the last joints are similar in size and form, hemispherical, armed with some larger, irregular, conical spines. Pores irregular, roundish, of variable sizes.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the single joints, a 0.02, b 0.03, c 0.02, d 0.05, e 0.04, f 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Artocapsa infraculeata, Haeckel.

Eucyrtidium infraculeatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 106, Taf. iv. fig. 13.

Shell subcylindrical, rough, with five annular septa. Length of the six joints = 2 : 3 : 4 : 4 : 4 : 3. The third, fourth, and fifth joints are nearly equal in length and breadth, whilst the second and sixth are cupola-shaped. The cephalis is very small, subspherical (regarded by Stöhr as a "large pore"), and bears a short conical horn. The last joint bears a bunch of basal spines.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the cephalis 0.02, second and sixth joints 0.03, third, fourth, and fifth joints 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr), Caltanisetta (Haeckel).

4. Artocapsa quadricamera, n. sp.

Shell spindle-shaped, smooth, with three sharp strictures. Length of the four joints = 2 : 3 : 4 : 8. The third joint is the broadest. The fourth joint is inversely conical, nearly as long as the three other joints together, and bears a strong, conical, basal spine, of half the length. The cephalis is small, subspherical, and bears a conical horn of the same length. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.17, breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.08.

Habitat.—Fossil in Barbados.

5. Artocapsa armata, n. sp.

Shell slender, inversely ovate, spiny, with six deep strictures. Length of the seven joints = 2 : 4 : 6 : 5 : 4 : 3 : 2. The third joint is the broadest, inflated, and much larger than the four following, which gradually decrease in size. The small, hemispherical cephalis bears a stout pyramidal horn of twice the length. The last hemispherical joint is armed with a bunch of stout spines, one of which is much the larger, and as long as the third joint. Pores irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.26, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.05, e 0.04, f 0.03, g 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4575 fathoms.

6. Artocapsa octocamera, n. sp.

Shell subcylindrical, smooth, with seven internal annular septa. Five joints (the third to the seventh) are nearly equal in size, while the second and eighth are cupola-shaped, somewhat longer. The cephalis is smaller, with a conical horn of the same length. The last joint bears a bunch of divergent, conical spines, of different lengths. Pores small, regular, circular.

Dimensions.—Length of the shell (with eight joints) 0.16, breadth 0.08. Length of the cephalis 0.016, second and eighth joints 0.033, each of the five other joints 0.022.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

7. Artocapsa elegans, n. sp. (Pl. [76], fig. 8).

Shell spindle-shaped, smooth, with eight internal, broad, annular septa. The second and third joints are the largest, the fourth and fifth of medium size, while the cephalis and the four last joints are nearly equal in length, and much shorter. The third joint is the largest. The subspherical cephalis bears a bristle-shaped horn of the same length, while the last joint is armed with a bunch of conical spines. Pores small, in the upper half of the shell regular, hexagonal, in the lower half irregular.

Dimensions.—Length of the shell (with nine joints) 0.2, breadth 0.09. Length of the first and the four last joints, each 0.014; of the fourth and fifth, each 0.02; of the third 0.04, second 0.05.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Legion IV. PHÆODARIA,

vel Cannopylea, vel Pansolenia (Pls. 99-128).

Phæodaria, Haeckel, 1879.

Tripylea, Hertwig, 1879.

Cannopylea, Haeckel, 1881.

Pansolenia, Haeckel, 1878.

Definition.—Radiolaria with a double membrane surrounding the central capsule, which bears on one pole of the main axis a peculiar astropyle, or a tubular main-opening, in the centre of a circular radiate operculum. Usually (but not constantly) a pair of small, lateral, accessory openings (or parapylæ) on the opposite pole of the main axis. Extracapsulum constantly with a phæodium, or with a voluminous aggregation of peculiar dark pigment bodies (phæodella) covering the astropyle of the central capsule. Skeleton siliceous or silicated, always extracapsular, very rarely wanting. Fundamental form very variable, originally monaxon, often dipleuric or bilateral.

The legion Phæodaria, or Cannopylea, in the extent here defined, was constituted by me in 1878, in my Protistenreich (p. 102) under the name Pansolenia. This name was given on the supposition that the skeleton of these interesting Radiolaria is always composed of hollow tubules, in contrast to that of the other Radiolaria, where it is never tubular. But I was soon convinced that this supposition was erroneous, that in a great part of the Pansolenia the skeleton is not composed of hollow tubules but of solid bars, and that a constant, very characteristic, and never failing mark of this group is to be found in the peculiar phæodium, a voluminous, constant, extracapsular pigment body. Therefore, in 1879, I changed the name into Phæodaria, and having discovered in the collection of the Challenger an astonishing number of new and wonderful types of this group, I described, in a preliminary note on it, four different orders and ten families with thirty-eight genera (Ueber die Phæodarien, eine neue Gruppe kieselschaliger mariner Rhizopoden; in Sitzungsberichte der Jenaischen Gesellschaft für Medicin und Naturwissenschaft. Sitzung vom 12th December 1879).

In the same year (1879), Richard Hertwig, in his excellent work entitled Der Organismus der Radiolarien, published the first accurate description of the intimate structure of the soft body of the Pansolenia, and mainly of their central capsule; and having always observed, in the few representatives examined by him, three openings in the capsule (one main-opening and two accessory openings), he called them Tripylea (loc. cit. p. 87), being guided by the erroneous supposition that these three openings are constant in all members of the group. But this is by no means the case. The two accessory openings are completely absent in several families, whilst in others their number is increased. A constant and very striking character, however, of all Phæodaria, is the peculiar structure of their tubular main-opening, which I call astropyle, with its radiate operculum and cannular proboscis. On account of this important and startling characteristic I proposed in 1881 to call this group Cannopylea. The two names Phæodaria and Cannopylea both express a very striking and quite constant character of these curious Radiolaria, whilst the two names Pansolenia and Tripylea are applicable only to a part of the whole legion.

The history of our knowledge of the Phæodaria is short, but very remarkable. Although hundreds of species, many of them cosmopolitan, are distributed over all oceans and all zones, although their size is in general much greater than that of the other Radiolaria (usually 1 to 2 mm., often even 5 to 10 mm. or more), and although their form and structure are usually striking, nevertheless the Phæodaria remained completely unknown up to the year 1859. During that year I observed the first forms living in the Gulf of Messina, and described and figured in 1862 in my Monograph five genera and seven species, viz., (1) Aulacantha scolymantha (p. 263), (2) Thalassoplancta cavispicula (p. 261, now Cannobelos cavispicula), (3) Aulosphæra trigonopa, and Aulosphæra elegantissima (p. 359), (4) Spongodictyum trigonizon (p. 459, now Sagoplegma trigonizon), and (5) Cœlodendrum ramosissimum, and Cœlodendrum gracillimum (p. 361). I recognised the structure of the three genera enumerated as 1, 3, and 5, as so remarkable and so different from that of the other Radiolaria, that I founded three peculiar families for them, the Aulacanthida, Aulosphærida, and Cœlodendrida.

The first note on the numerous remarkable Phæodaria discovered by the Challenger, and mainly on the large-sized inhabitants of the deep-sea, was published in 1876 by Dr. John Murray, in his Preliminary Reports on Work done on Board the Challenger (Proc. Roy. Soc., vol. xxiv., read March 16, 1876). He pointed out (loc. cit., p. 535), that the tow-nets, sent down to a great depth (according to a new plan, adopted in April 1875) brought up on every occasion a great many new and peculiar Rhizopods, which had never been observed in the nets used near the surface. "The shells of all have an exceedingly beautiful tracery, a fenestrated appearance often, which a closer examination shows to be caused by pit-like depressions. Some have only one, others have several openings, through which the sarcode flows. The sarcode of all these deep-sea Rhizopods has many large black-brown pigment-cells. At times they come up with a good deal of the sarcode outside of the shell; and two specimens have been seen to throw out elongated pseudopodia" (loc. cit., p. 536). Dr. John Murray distinguished at that time not less than fifty species of these interesting deep-sea Rhizopods and called them provisionally Challengerida; a term which we retain here for the largest and most characteristic family. He gave at the same time, in an accompanying plate (xxiv.), six figures of new Phæodaria, the names of which (as found by me in 1879 in the corresponding preparations) are the following; (1) Challengeria naresii, (2) Challengeria aldrichii, (3) Bivalva compressa (now = Conchopsis compressa), (4) Tuscarora belknapii, (5) Challengeria circopora (now = Circoporus sexfurcus), and (6) Haeckeliana porcellana. A great number of these Challengerida (twenty species) were afterwards figured by Dr. John Murray in the Narrative of the Cruise of H.M.S. Challenger, 1885, vol. i. part 1, p. 226, Pl. A; viz., fourteen species of Challengeria and six species of Tuscarora.

The most important advance in the knowledge which we had of the peculiar organisation of the Phæodaria, was made by the accurate description which Richard Hertwig published, in 1879, of the intimate structure of their central capsule, and mainly of its peculiar openings. He examined living at Messina the following three forms, described in my Monograph; (1) Aulacantha scolymantha, (2) Aulosphæra elegantissima, and (3) Cœlodendrum ramosissimum. Besides, he described an interesting new genus, Cœlacantha anchorata; and another new form, which he placed in the Aulosphærida, as Aulosphæra gracilis, but which really was a new genus of Sagosphærida, here described as Sagoscena gracilis. Finally, Hertwig first discovered that the peculiar bodies, described by Ehrenberg as Dictyocha and placed by him in the Diatomea (Polygastrica), were the isolated pieces of the skeleton of a true Phæodarium, and that they were scattered loosely in great numbers over the surface of the jelly-sphere, just as are the hollow spicula of Thalassoplancta or Cannobelos.

The six species mentioned, of which Hertwig gave a very accurate description and very instructive figures, belong to six different genera, and these represent six different families of Phæodaria, viz.; Aulacanthida, Aulosphærida, Cœlodendrida, Cannosphærida, Sagosphærida and Cannorrhaphida. He found that all these six forms, in spite of great differences in the form and structure of their skeleton, were identical in the structure of the central capsule; and since he observed constantly three openings in its double wall (a large main-opening on the oral pole, and a pair of lateral accessory openings on the aboral pole of its main axis) he called them Tripylea (loc. cit., p. 87, 94). But he also pointed out the remarkable shape of their voluminous extracapsular body, and especially the characteristic position, size, colour and composition of the large pigment body, which I had called the phæodium.

The accurate description of the gigantic and elegant skeleton of a new Phæodarium, surpassing all other known Radiolaria in its extraordinary size (15 mm.), was published in 1882 by O. Bütschli (in Zeitschr. f. wiss. Zool., vol. xxxvi. p. 486, Taf. xxxi.). He called it Cœlothamnus davidoffii, in honour of its discoverer, who had found it floating on the surface of the Gulf of Villafranca, near Nice. He placed it among the Cœlodendrida; it belongs, however, to that part of this group which possesses a nasal tube, and which I afterwards separated under the name Cœlographida.

The total number of Phæodaria, hitherto described and illustrated by figures, amounts therefore to seventeen species, viz., the seven species first described by myself (in 1862); the six new species figured by Dr. John Murray (in 1876); the three new species discovered by Hertwig (in 1879) and the single species last-mentioned described by Bütschli (in 1882). The rich collection of the Challenger has added to this small number such an astonishing wealth of new and remarkable forms, that I can describe in the following system of Phæodaria not less than eighty-four genera and four hundred and sixty-five species. These belong to fifteen different families and four different orders. But this great number is probably only a small part of the numerous interesting Phæodaria, which are abundantly distributed over all the oceans; those (e.g.) of the Indian and of the Arctic Oceans are almost unknown.

The great majority of these wonderful Phæodaria are inhabitants of the deep-sea, mainly of the southern hemisphere, and are so common in many stations explored by the Challenger, that its collection contains many thousands (or rather hundreds of thousands) of well-preserved specimens. A smaller part of the legion is found on the surface, widely distributed over all oceans; some of these are very common (as, e.g., Aulacantha, Aulosphæra, Sagosphæra, Cœlodendrum, Castanella, &c.) and it is difficult to explain how they could entirely escape the eyes of all former observers.

The three general characters which distinguish the Phæodaria easily and constantly from all the other Radiolaria are the following:—(1) the double membrane, a thick outer and a thin inner envelope, of the big central capsule; (2) its typical main-opening or astropyle, placed on the oral pole of the main axis, and distinguished by a peculiar radiate operculum, with tubular proboscis; (3) the phæodium, or the peculiar voluminous pigment-body, which constantly lies in the oral half of the calymma, surrounds the oral part of the central capsule, and is composed of numerous phæodella, or singular pigment-granules of green, olive, brown or black colour.

Besides these three general and never failing marks of the Phæodaria, the majority of this legion (but by no means all) possess the three following peculiarities; (1) two parapylæ or accessory openings of the central capsule, placed laterally (at the right and left) on the aboral pole of the main axis (wanting in the Challengerida, Medusettida, Castanellida, and perhaps in some other families); (2) a characteristic skeleton which is always extracapsular, wanting only in the Phæodinida, incomplete in the Cannorrhaphida and Aulacanthida, but perfectly developed and of very various shapes in the twelve other families; usually this silicated skeleton is composed of hollow tubules, which are filled up by jelly (Pansolenia); but in some families it is composed of ordinary solid network, not different from that of the other Radiolaria, e.g., especially in the Castanellida and Sagosphærida; (3) an extraordinary size of the body, as well of the central capsule and its nucleus, as of the extracapsular skeleton; the majority of Phæodaria have a diameter of 1 to 2 mm., and are therefore from ten to twenty times as large as the majority of the other Radiolaria; in some gigantic forms the diameter of the unicellular body reaches 20 or even 30 mm.

The Central Capsule of the Phæodaria is the most important part of their body and preserves in all families of this legion the same essential structure, and nearly the same form, in striking contrast to the extraordinary variety and complication of the skeleton. As already mentioned, it differs from the central capsule of all the other Radiolaria in two most important peculiarities; firstly, the double membrane of the spheroidal capsule, and secondly, the singular structure of its constant main-opening, the astropyle. A third constant character is the considerable size of the enclosed nucleus, the diameter of which usually equals about half of that of the capsule itself.

The diameter of the capsule is, in the majority of Phæodaria, 0.1 to 0.2 mm., often also 0.3 to 0.4, rarely more than 0.5, or less than 0.05 mm.

The position of the central capsule is somewhat different in the four orders into which we have divided the Phæodaria. It lies in the centre of the spherical, concentric calymma in all the Phæocystina, or in those Phæodaria which possess no complete lattice-shell—Phæodinida, Cannorrhaphida, and Aulacanthida (Pls. [101]-[105]). The Phæosphæria (comprising the Orosphærida, Sagosphærida, Aulosphærida, and Cannosphærida, Pls. [106]-[112]) all possess a very big, usually spherical lattice-shell, and here the central capsule is much smaller than the latter and lies in its centre. Another position is constantly occupied by the central capsule in all Phæogromia (Pls. [99], [100], [113]-[120]; the families Challengerida, Medusettida, Castanellida, Circoporida, Tuscarorida), which have a peculiar mouth on the lattice-shell, placed on the oral pole of its main axis; the central capsule lies in the opposite aboral half of the shell cavity. The Phæoconchia finally (Pls. [121]-[128], the families Concharida, Cœlodendrida, and Cœlographida) all possess a bivalved shell, and the capsule is here enclosed between the two valves of the shell.

The form of the central capsule is constantly spheroidal, slightly depressed in the direction of the main axis, and therefore comparable to the spheroidal form of our globe. The depression is generally very slight, so that the proportion of the minor vertical main axis to the major horizontal or equatorial axis is about 4 : 5 or 5 : 6, often even 8 : 9 or less; but sometimes the proportion becomes 3 : 4, or even 2 : 3, so that the capsule becomes nearly lenticular; very rarely its form becomes almost perfectly spherical (Pl. [101], fig. 1). The main axis stands always vertically, and is distinctly marked by the peculiar shape of the astropyle, placed on its oral pole. Usually this pole, in the living and freely floating Phæodaria seems to be the lower pole, directed downwards (as also in the Nassellaria); but in some families it seems to be inversely directed upwards, as in the Challengerida and Tuscarorida, (Pls. [99], [100]).

The two membranes of the central capsule possess in all Phæodaria a very different shape, and were in all preparations which I could accurately examine (some hundreds belonging to all families) separated by a clear, rather wide interval, filled up either by a colourless fluid or by a structureless jelly (Pl. [103], fig. 1; Pl. [123], figs. 8, 9, &c.). They are in direct connection only at the openings. In the living Phæodaria, however, their distance is very small, or they are in immediate contact without any interval (Pl. [101], fig. 10; Pl. [102], fig. 1). According to the observations of Hertwig, the two membranes are always in close contact, and without interspace, in the living Phæodaria; and the space between them is an artificial product due to the influence of the preserving fluid or of certain chemical agents. In every case it is very easy to separate both membranes completely, except at the openings, where they are in direct connection. We distinguish both membranes shortly as ectocapsa and endocapsa.

The ectocapsa, or the outer membrane of the central capsule, is rather firm and durable, double-contoured, elastic and difficult to destroy. Its physical and chemical qualities seem to approach those of chitin. It becomes, however, stained red by carmine, and yellow by nitric acid. Usually it appears structureless and refracts the light strongly. In a few cases, however, it exhibits, when examined by strong lenses, a fine punctation; and in some Aulacanthida (especially in some big forms of Aulographis and Aulospathis) the entire ectocapsa was densely covered with peculiar curved, or S-shaped dark corpuscles (Pl. [114], fig. 13). They were all of the same length, about 0.01, and seemed to lie on its inner face.

The endocapsa, or the inner membrane of the central capsule, is much thinner than the outer, with which it is in immediate connection only at the openings. It encloses the entire contents of the capsule, and becomes very distinct, as soon as the latter are dissolved by chemical agents, or stained by carmine. In the majority of well-preserved preparations it is irregularly plicated, and resembles a thin, but firm, crumpled paper. Isolated pieces of the endocapsa are completely structureless, but exhibit also a considerable resistance, in spite of their minute thickness.

The openings of the central capsule exhibit in the Phæodaria a greater variety than their discoverer, R. Hertwig, supposed. The majority of the legion, certainly, possess the three openings described by him, and are therefore true Tripylea. Some families, however, have only one opening, the astropyle, which is generally present (Challengerida, Medusettida, Castanellida, and Phæocolla among the Phæodinida, Pl. [101], fig. 1). In some other families there is a variable number of accessory openings or parapylæ, one, three, or more, e.g., especially in the Circoporida and Tuscarorida. The former may be called Astropylea, the latter Sporopylea. Thus only a single opening to the central capsule is constant in all Phæodaria without exception, and that is the astropyle, or the large main-opening with its peculiar structure.

The astropyle, or the single constant main-opening of the central capsule, is distinguished by a very remarkable structure, and is sufficient of itself to separate the Phæodaria from all the other Radiolaria, and from the other Rhizopoda in general. It is always placed on the oral pole of the main axis, forming here a peculiar cap-shaped or flatly conical elevation, the centre of which is prolonged into a short, cylindrical tubule; we call the latter shortly a proboscis, and the former an operculum. To understand better the different forms which these important parts assume in the different families, compare Pl. [101], figs. 1-6; Pl. [102], fig. 1; Pl. [103], fig. 1; Pl. [104], figs. 1-3; Pl. [111], fig. 2; Pl. [123], figs. 1-9; Pl. [127], figs. 4-6; Pl. [128], fig. 2, &c. Compare also the first very accurate figures which R. Hertwig has given in 1879 (loc. cit.) in his Taf. x.

The operculum of the astropyle, the most important part of this main opening ("der Oeffnungshof der Hauptöffnung," in the description of Hertwig), is a circular convex plate, always more strongly vaulted than the surrounding part of the capsule membrane, and is sharply separated from it by a circular, often thickened and double-contoured margin. The operculum covers the main-opening like the lid of a tea-kettle, and the proboscis arising from its centre is comparable to the handle of that lid. The diameter of the circular operculum is usually about half as long (rarely as long) as the radius of the central capsule, therefore in the majority of Phæodaria 0.03 to 0.06, sometimes 0.1 and more. Its form is sometimes more conical, sometimes more like a mamma. Its height is usually about equal to half its diameter. It always exhibits a very distinct radial striation, produced by numerous prominent radial ribs, which arise in the centre and end at the circular sharply truncated margin. The usual number of these radial ribs may be, in the operculum of smaller capsules, from thirty to fifty, in those of medium size from sixty to ninety, and in the largest two hundred to three hundred or more. Usually the ribs are simple (Pl. [101], figs. 1, 2, 6, 10; Pl. [127], figs. 4-6; also in all figures given by Hertwig); but sometimes, mainly in the biggest Aulacanthida, they are distinctly branched in a centrifugal direction (Pl. [114], fig. 13; Pl. [115], fig. 3). Hertwig is of the opinion that the radial ribs are thickened ridges of the endocapsa ("leistenartige Verdickungen der inneren Membran"), and that the ectocapsa covering it is structureless (compare his figs. 1 and 1a, in Taf. x.). But I am convinced now, by numerous experiments and observations, that the radiate operculum is a part of the outer, not of the inner membrane. That part of the latter which lies immediately beyond the former, and which may be called the "inner operculum," also exhibits usually a fine radial striation; but this is probably only the cast of the stronger and much more prominent radial ribbing of the "outer operculum" belonging to the ectocapsa. The latter exhibits a large circular opening with thickened margin, when the radiate operculum is taken from it. The operculum becomes stained intensely red by carmine, yellow by nitric acid, corresponding to the ectocapsa, the main-opening of which is closed by it.

The proboscis, or the cylindrical tubule, which arises in the centre of the operculum, is often rather short, and bears the same relation to it as the nipple does to the human breast (Pl. [104], fig. 2). But usually it is more or less prolonged and often about as long as the radius of the capsule, rarely nearly as long as its diameter (Pl. [101], fig. 1). Its form is usually a slender cylinder, sometimes somewhat conical and tapering towards the distal end. It is more or less curved or S-shaped in the majority of preparations (Pl. [115], fig. 3; Pl. [127], fig. 6, &c.). Its thin wall is a direct prolongation of the outer membrane of the capsule, therefore it appears as a direct apophysis of the operculum, when this is detached from the latter. The opening at the distal end of the proboscis, through which the endosarc is thrown out, is circular.

The parapylæ, or the accessory openings of the central capsule, exhibit in all Phæodaria the same form and structure, but vary in number and disposition. They are recognised with difficulty in the smaller species, since they are always of small size, and may be easily overlooked. They seem to be completely wanting in the following families:—Challengerida (Pl. [99]), Medusettida (Pls. [118]-[120]), Castanellida (Pl. [113]), and in single genera of other families, as in Phæocolla (Pl. [101], fig. 1). The majority of Phæodaria seem to possess the two lateral parapylæ, first described by Hertwig, placed at a variable distance on each side of the aboral pole, to the right and left (Pl. [101], figs. 2, 6, 10; Pl. [103], fig. 1a; Pl. [104], figs. 1, 2a; Pl. [123], figs. 1, 8a &c.). The horizontal axis, on which the two parapylæ lie, is the the frontal or lateral axis; and the plane, which passes through the three openings of these "Tripylea," is the frontal or lateral plane. The number of the parapylæ seems to be variable in the two families, Circoporida and Tuscarorida, which also differ from the other Phæodaria in the peculiar (porcellanous) structure of their shell-wall. The number seems to vary even in the single species of one genus; and the following cases may be found: (A) a single parapyle, placed on the aboral pole of the main axis and directly opposed to the astropyle (on the oral pole), as in Tuscaridium (Pl. [100], fig. 8); (B) three equidistant parapylæ, one of which is placed in the sagittal plane, and the two others one on each side of it, to the right and left, is in Tuscarora (Pl. [100], figs. 1-6); the three parapylæ seem to correspond here to the three long feet, or the tubular aboral apophyses of the shell, which are arranged in a similar manner to the three cortinar feet of the Nassellaria; (C) four equidistant parapylæ, placed in pairs on the poles of the diagonal axes of a horizontal plane, as in Tuscarora (Pl. [100], fig. 7); they seem here to correspond to the four crossed aboral feet; (D) six to eight or more parapylæ probably in the different genera of Circoporida (Pls. [114]-[117]); perhaps each radial tube, which is surrounded on its base by a circle of pores, here corresponds to a separate parapyle. The number of well-preserved central capsules belonging to the two latter families, however, which I could examine was relatively small and their examination very difficult; therefore these numbers are not stated with satisfactory certainty and require a further more accurate examination. The minute structure of the parapylæ (or "Neben-Oeffnungen") has been described already very accurately by Hertwig (loc. cit., p. 95, Taf. x. figs. 1-11b). The two membranes of the capsule are in direct and immediate connection on each parapyle. The strong outer membrane arises in the form of a ring or of a short cylindrical tubule (collare paraboscidis or "Oeffnungshals"), is then reflected inwards, and connected at the bottom of the cylindrical cavity with the delicate inner membrane. From this connective ring arises a short conical or cylindrical tubule, which we call shortly the "paraboscis." According to Hertwig (who calls it "Oeffnungskegel") the paraboscis is a direct prolongation of the inner membrane only. My own observations have led me to the opinion, that the paraboscis of each parapyle is a direct prolongation of the outer membrane (similarly to the larger proboscis of the astropyle), and that the basal connective ring is, therefore, the inner opening of the paraboscis, through which the entosarc enters, being protruded through its outer circular opening. Usually the paraboscis of each parapyle is only a short cylinder, arising by a conical base; but sometimes, especially in some Aulosphærida and Sagosphærida, it is prolonged into a slender tubule, nearly as long as the radius of the central capsule. It has been already figured by Hertwig (loc. cit., Taf. x. figs. 6-8). It seems, therefore, that the paraboscis of the accessory openings is developed in a way similar to the proboscis of the main-opening, and that the chief difference between the two is indicated by the large radiate operculum of the latter.

The cavity of the endocapsa, or the spheroidal space enclosed by the inner membrane of the central capsule, is filled up in its central part by the big nucleus, in its peripheral part by the endoplasm, or by the internal protoplasm, which is in communication with the outer or extracapsular protoplasm by the openings of that capsule. The endoplasm, or the intracapsular sarcode, is rather opaque, finely granulated, and usually filled up by numerous small clear spherules of equal size, which are more or less regularly arranged and equidistant. These spherules have usually a diameter of 0.01 to 0.015, rarely more than 0.02 or less than 0.005 mm.; their size is generally equal in each capsule. They have been already described and figured in my Monograph, as "wasserhelle kugelige Bläschen," and are probably vacuoles or small vesicles filled up by jelly or by a clear fluid. Usually each vesicle contains a small dark granule of fat, or a group of such granules connected together; and in these Hertwig observed a vibrating molecular motion. The central capsule of many Phæodaria contains, besides the vacuoles, often granules of pigment (usually red or yellow) and sometimes numerous groups of small crystals, placed mainly beyond the operculum of the astropyle (Pl. [127], figs. 4-7). The outer layer of the endoplasm, placed immediately beyond the endocapsa, often exhibits a fine striation, as if composed of delicate fibrillæ. This fibrillar striation is usually most distinct on the base of the openings, where also the endoplasm becomes stained very intensely by carmine. The astropyle as well as the parapylæ often exhibit here, when observed from the face, a distinct radial striation (compare Hertwig, loc. cit., p. 98, Taf. x. figs. 6-14) Perhaps the radiate shape of the operculum is only produced by radial folds of the endocapsa placed beyond it, and these folds may be in turn the product of the radial fibrillæ, which are prominent beyond the astropyle. On the other hand, these fibrillæ may be compared to the muscular fibrillæ or "myophane filaments" in the ectosarc of the Infusoria, and may perhaps effect by their contraction a dilatation of the openings of the capsule.

The nucleus of the Phæodaria is always very large, usually about half or two thirds as broad as the central capsule and placed either in its centre, or sometimes nearer to one pole of the main axis, which is common to the capsule and its nucleus. Therefore the diameter of the latter is usually half or even two thirds of that of the capsule, and may be in the majority 0.05 to 0.15, often 0.2 to 0.3, rarely more than 0.4 or less than 0.01 mm. The form of the nucleus is rarely spherical, usually spheroidal, and it is more depressed in the direction of the main axis than the capsule itself. In my Monograph, where I gave the first description of it, I called it "Binnenbläschen." The membrane of the vesicular nucleus is thin but rather firm, and contains a rather clear, finely granulated substance, in which numerous nucleoli are usually scattered. (Compare Pl. [101], figs. 1-10; Pl. [102]-[104]; Pl. [123]; Pl.[127], &c.; the nucleus is marked by n, the nucleoli by l.)

The nucleoli are very different in respect to their form, size, number and arrangement. Since these differences are very great even in different specimens of a single species (as, e.g., in the common cosmopolitan Aulacantha scolymantha, Aulosphæra trigonopa, Cœlodendrum ramosissimum, &c.), it is probable that they represent different stages of development and multiplication, and that the smallest fragments of the nucleoli, or the final results of their repeated division, become the nuclei of the flagellate spores, which are developed in the Phæodaria just as in the other Radiolaria. In the majority of nuclei examined, the number of the enclosed nucleoli proved to be very great, fifty to eighty or more, often some hundreds, the greater their number the smaller their size. Their form is usually irregular, roundish, or even amœboid—probably the result of amœbiform motions (Pl. [101], fig. 1). Sometimes the nucleoli were regularly spherical, equidistant, and connected apparently by a delicate network (Pl. [101], fig. 2). (Compare Pl. [102]-[104], [111], [123], and also Taf. x. of Hertwig, loc. cit.).

The calymma, or the extracapsular jelly-veil, is in the Phæodaria always well developed and usually much larger than the enclosed central capsule. The entire volume of the calymma may be three to six times as great as that of the capsule in the majority of this legion; but in the large Aulacanthida, Aulosphærida, Cœlodendrida, Cœlographida, &c., the volume of the former is twenty to fifty as great as that of the latter, or even more. The jelly substance is rather firm and consistent, clear, structureless, and becomes more or less intensely stained by carmine. In the larger forms it is often filled by numerous large alveoles, which are usually absent in the smaller forms. These extracapsular alveoles are most strongly developed in the calymma of the Phæocystina, or the Phæodaria with incomplete skeleton, embracing the three families Phæodinida, Cannorrhaphida and Aulacanthida (Pls. [101]-[104]). Usually the calymma is here very voluminous and entirely filled up by large alveoles, which are either spherical, irregularly roundish, or polyhedral by mutual compression. These alveoles or vacuoles have no peculiar wall, but are only cavities in the homogeneous substance of the jelly, and are filled by a clear aqueous fluid. Between these the network of the anastomosing pseudopodia is expanded. They exhibit, therefore, the same shape, as was first observed in Thalassicolla and in the Polycyttaria (Collozoida, Sphærozoida and Collosphærida).

The relation of the calymma to the skeleton is in the Phæodaria of the same importance as in the other Radiolaria, and we may also here distinguish a primary and a secondary calymma. The primary calymma is that on the surface of which at a certain period of life (in the "shell-building period") the fenestrated shell is secreted in the majority of Phæodaria. The secondary calymma, however, is formed after this period, and envelops the shell itself as well as its apophyses externally. Usually the entire skeleton seems to be enveloped by the secondary calymma.

The parts of the extracapsular body, which are enclosed in the gelatinous calymma possess a peculiar importance in the Phæodaria; these are firstly the sarcomatrix and the pseudopodia arising from it, and secondly the phæodium. The sarcomatrix, or the layer of extracapsular sarcode (ectoplasm), which immediately surrounds the central capsule is very thick and more strongly developed in all Phæodaria than in all other Radiolaria. Its extraordinary size has been already mentioned by Hertwig (1879, loc. cit., p. 99). It is in direct connection with the intracapsular sarcode (or the endoplasm) only by the openings of the central capsule, and mainly by the astropyle. Very numerous radial pseudopodia arise everywhere from the sarcomatrix and run to the surface of the calymma, usually forming a rich network in it by means of numerous branches and anastomoses (compare Pl. [101]-[104]). On the surface of the calymma the meshes of this network are very numerous, and there arise from its nodal points the terminal pseudopodia, which float freely in the surrounding water. The metamorphoses of this network of sarcode, the perpetual changes in the number and size of its meshes, and the movements of the sarcode streams as well as of the small granules running in it, are always very manifest in the Phæodaria and in the big forms of this legion (mainly in the Aulacanthida) they are better observed than in the majority of other Radiolaria. In many Phæodaria (and perhaps in all) a part of the pseudopodia seems to have undergone a local differentiation, for special physiological purposes; and Hertwig has described a peculiar conical contractile body, which arises in Cœlodendrum between the two parapylæ (loc. cit., p. 100, fig. 3). Further examination of these interesting organs in living Phæodaria is required. Usually the sarcode, issuing from the openings of the capsule, forms a stronger cylinder, with peculiar movements.

The phæodium, or the peculiar dark extracapsular pigment-body of the Phæodaria, is one of the most important and most characteristic parts of their organisation, and has induced me to derive their name from it; it is not less typical for the whole legion, than the astropyle with its radiate operculum and the proboscis; and both these important parts are always in direct topographical and physiological connection. Whilst I have missed the phæodium in no Phæodarium in which the soft body was well preserved, I have not found it in any other Radiolaria; for the similar extracapsular pigment bodies, which are found in some species of Thalassicolla and some other Sphærellaria, have a composition and signification different from that of the phæodium—an exclusive peculiarity of the Phæodaria.

The typical importance of the phæodium for all members of this legion is proved by the following five facts:—(1) its constant presence in all Phæodaria; (2) its constant excentric position in the oral half of the calymma; (3) its constant relation to the astropyle, the operculum and the proboscis of which is always surrounded by it; (4) its constant considerable size, its volume being usually greater than that of the central capsule, the aboral half of which is covered by it; (5) its constant colour and morphological as well as chemical composition. These five facts together demonstrate by their absolute constancy the high morphological and physiological importance of the phæodium for this peculiar subclass of Radiolaria, although its true nature is difficult to make out, and its main function is not yet sufficiently known.

The first remarks that have been made on the phæodium were published in 1862 in my Monograph, where I noticed the peculiar dark brown extracapsular pigment body and its excentric position covering only one-half of the central capsule, in Aulacantha (p. 263, Taf. ii. figs. 1, 2), in Thalassoplancta (p. 262, Taf. iii. fig. 10), and in Cœlodendrum (p. 361, Taf. xxxii. fig. 1). Its general presence and peculiar composition were first recognised by Dr. John Murray, who had, during the Challenger Expedition, the first opportunity of examining many big living Phæodaria brought up from great depths. He gives in his first Report (1876, loc. cit., p. 536), the following important notice:—"The sarcode of all these deep-sea Rhizopods has many large black-brown pigment-cells. Small bioplasts are scattered through the sarcode. These collect into capsular-like clumps when the animal is at rest, and are quickly coloured by carmine." In 1877 Dr. John Murray sent me the wonderful collection of Phæodaria brought home by the Challenger, and I had now the best opportunity for examining the phæodium in hundreds of well-preserved specimens. Supported by these extensive observations, I gave, in 1879, in a preliminary paper,[[273]] a fuller description of the phæodium, and of the phæodella (or the peculiar dark pigment-granules composing it). At the same time R. Hertwig published his observations on the big living Tripylea examined by him at Messina, and pointed out particularly that the constant presence, composition, and arrangement of this excentric extracapsular pigment-body was most characteristic, and sufficient in itself to distinguish this group from all the other Radiolaria (1879, loc. cit., p. 99).

The most striking peculiarity of the phæodium, and the most important on account of its absolute constancy, is its excentric position, covering only the oral hemisphere of the central capsule, and wholly or partly wanting on the aboral hemisphere. This constant topographical relation to the capsule never fails, and may be always observed at the first glance, when the body is seen from the side (the main axis of the capsule being perpendicular to the axis of the eye of the observer), (compare Pl. [101], figs. 6, 10; Pl. [102], fig. 1; Pl. [103], fig. 1, &c.). The phæodium envelops, therefore, the oral half of the capsule completely, and especially the astropyle in its centre; hence, the radiate operculum and the proboscis arising from the latter cannot be seen usually before the former is removed. The general form of the entire phæodium, in consequence of this excentric position, is concavo-convex (or crescentic in longitudinal section), its concave face embracing the oral or anterior face of the capsule, and its convex face being turned to the surface of the calymma.

The topographical relation of the phæodium to the surrounding shell is also very characteristic in the suborder Phæogromia, or in those Phæodaria which possess a peculiar shell-mouth placed on the oral pole of its main axis. Here the capsule is always placed in the aboral half of the shell-cavity, the phæodium in its oral half, separating the astropyle from the mouth of the shell, both of which lie in the main axis; as in the Challengerida (Pl. [99]), Tuscarorida (Pl. [100]), Castanellida (Pl. [113]), Circoporida (Pl. [115]), and Medusettida (Pl. [118]-[120]). In this suborder (the Phæogromia), the volume of the phæodium may be, on an average, about as great as that of the central capsule, whilst in the majority of other Phæodaria it is much greater than the latter.

A similar topographical relation between the phæodium and the enclosing shell, as in the Phæogromia, also exists in the suborder Phæoconchia, or in those Phæodaria, which are distinguished from all the others by the possession of a bivalved shell (Pl. [121]-[128]). The two valves of this curious shell, which resembles that of the Brachiopoda, are dorsal and ventral, and the tripylean central capsule is always so placed between them that its two lateral parapylæ (right and left) lie in the frontal plane of the shell, where a large frontal fissure opens between the opposed margins of the two hemispherical or cap-shaped valves. The phæodium is also placed here on the oral half of the capsule and surrounds its astropyle; but it exhibits some differences in the three families of Phæoconchia.

The Concharida, the bivalved shell of which is simple, and without tubular apophyses (Pl. [123]-[125]), possess a relatively small central capsule, which usually fills up only the third or fourth part of the shell-cavity. This is the aboral or posterior part, on the apex of which both valves are united by a ligament in some Concharida (Pl. [123], figs. 8, 9). The oral or anterior part of the shell-cavity (usually two-thirds or more) is filled up by the phæodium, and this is usually bifid, being divided by a frontal constriction into two wings or lobes; the dorsal wing is hidden in the upper valve of the shell, the ventral wing in the lower valve; both wings are usually united only by a small central bridge, and this bridge of the phæodium is pierced in its centre by the proboscis of the astropyle (Pl. [124], figs. 6, 10; Pl. [123], figs. 8, 9).

The Cœlodendrida have a different shape (Pl. [121]). Their bivalved shell is relatively small and tiny, and bears on the two poles of the sagittal axis two conical apophyses or galeæ, from each of which three or four very large, dichotomously branched tubes arise. The central capsule fills up the cavity of the bivalved shell almost entirely, and the voluminous dark phæodium envelops both to such an extent that the shell and the enclosed capsule are often hidden in it completely. Therefore I arrived in my first description of Cœlodendrum (1862, loc. cit.) at the erroneous conclusion that the capsule lies outside, not inside the shell. The first accurate figure and description of its structure was given in 1879, by Hertwig (loc. cit., p. 99, Taf. x. fig. 3). The central capsule (v) is here separated from the bivalved shell (m) only by a very small distance, and the oral part of both is hidden in the phæodium. I find, however, in the majority of the numerous preparations of the Challenger collection, the volume of the phæodium much greater, and it often envelops the entire shell.

The Cœlographida, finally, have a phæodium of the most remarkable shape, since in their bivalved shell a peculiar reserve store or magazine of phæodella, which we call the "phæocapsa" is developed for it (Pl. [126]-[128], g.t.m.). The bivalved shell has in these most perfect Phæodaria a structure similar to that in the Cœlodendrida; but they differ from the latter in the stronger development, and greater differentiation of the two apical galeæ, and the large hollow tubes arising from them. These two helmet-shaped cupolæ, the galeæ (g), which arise from the two valves on the poles of the sagittal axis, are in the Cœlographida usually larger than the valves themselves, and are not closed, as in the Cœlodendrida, but open by a tubular apophysis at their base, the nasal tube or rhinocanna (t). The apex of the galea is connected with the open mouth of the rhinocanna by a single or double frenulum (b). The two nasal tubes or rhinocannæ (a dorsal and a ventral) lie in the sagittal plane of the body and run from the base of each galea along the anterior convexity of the valve to its oral margin. Here is placed the proboscis of the astropyle, between the two opposed mouths of the rhinocannæ (Pl. [128], fig. 2). The phæodium is usually hidden entirely in the two phæocapsæ, which are composed of the two galeæ (g), and the two rhinocannæ arising from them (Pl. [127], figs. 4-9). A part of the phæodella is usually thrown out by the mouth of the latter (m).

The characteristic colour of the phæodium exhibits numerous different tints between green, brown, and black. It seems to be in the majority blackish-brown or greenish-brown, very often olive, more rarely almost quite green or red-brown. Usually the colour is so dark, intense and opaque, that the parts enclosed by the phæodium, mainly the oral hemisphere of the central capsule and the astropyle, are completely hidden in it. The chemical composition of the phæodium demands further accurate researches; unfortunately I have not been able to make out its true nature, since numerous different experiments furnished no certain general results.

The phæodella, or the pigment-corpuscles, which compose the phæodium, aggregated in hundreds, and in the bigger species in thousands, are usually spherical, sometimes somewhat ellipsoidal, at other times spheroidal or lenticular; but usually numerous smaller, irregular, roundish particles are intermingled between the larger and more regular corpuscles, and often the main mass forms a very fine black powder. The size of the phæodella is very variable, not only in the different species, but also in one and the same individual. The larger phæodella have a diameter of 0.01 to 0.02, the smaller of 0.004 to 0.008 mm.; but there also occur very big forms of 0.04 to 0.05 mm., or even more, and very small ones of 0.001 mm. or less. Usually the phæodium appears as an aggregate of numerous larger and smaller phæodella, which are very different in size as well as in the intensity and tint of their colour, and are irregularly crowded in a black, powder-like substance.

The morphological nature of the phæodella is also difficult to make out. I have already pointed out in my first description of Aulacantha, Thalassoplancta and Cœlodendrum (1862, loc. cit.), that a great part of these pigment-corpuscles are true cells, composed of a nucleus and protoplasm, which contains granules of pigment, and is enveloped by a membrane. Dr. John Murray, who had during the Challenger voyage the opportunity of examining numerous different living Phæodaria, and staining them by carmine, also asserts that a great part of those dark corpuscles are "large black-brown pigment-cells" (1876, loc. cit., p. 536). Numerous preparations of the Challenger collection, well preserved in glycerine, and stained by carmine, contain Phæodaria belonging to different families, the phæodium of which contains numerous such "pigment-cells," with a dark red nucleus, and so similar are these cells, that every histologist should recognise them. But in strange contrast to this is the fact, that in numerous other mountings, prepared in the same manner, not a single cell of this kind is found in the phæodium, and that the latter is composed only of irregular pigment-granules. In many Phæodaria belonging to different families I, like Hertwig, could not find a single true nucleated cell in the phæodium.

A great part of the Phæodaria, and usually the bigger forms of Aulacanthida, Cannorrhaphida, Cœlodendrida, Cœlographida, &c., exhibit a peculiar structure of the larger phæodella, viz., a fine parallel striation (Pl. [101], figs. 3, 6; Pl. [102], fig. 1; Pl. [103], fig. 1; Pl. [104], figs. 1-3, &c.). In each phæodellum may be counted about ten to twenty such fine parallel stripes (more in the greater, less in the smaller forms); and in the ellipsoidal phæodella the stripes are either transverse rings, perpendicular to their main axis, or ascending obliquely; they often resemble the convoluted spiral filament of a thread-cell or nettle-cell of an Acaleph. Sometimes these parallel transverse stripes are very striking. Another structure is seen in larger phæodella, namely an aggregate or cluster of smaller globules, often of equal size, resembling a small morula. All these minute structures of the phæodella as well as their changes in the living Phæodaria, require a far more extensive examination (by means of strong lenses and different chemical reagents), than I could, unfortunately, devote to them.

The physiological signification of the phæodella, therefore, is at present not yet known; but the general facts quoted above, their constant presence, position, volume, and composition, make it probable that their physiological value in the Phæodarian organism is very great. The following hypotheses may be taken provisionally into consideration:—A. The phæodella are peculiar symbiontes, or unicellular algæ, comparable to the xanthellæ or zooxanthellæ of the other Radiolaria. This hypothesis is probably correct for those phæodella which are true nucleated cells; and the more so, as the majority of Phæodaria do not exhibit those common yellow xanthellæ, which are usually found in the Spumellaria and Nassellaria. It is even possible that the latter are absent in all Phæodaria. B. The phæodella are dark pigment-bodies, which absorb light and heat in a manner similar to the simple "pigment-eyes" of many lower animals, and may therefore be optical sense-organs of the Phæodaria. This hypothesis may be supported by a comparison with the large-eyed unicellular Protist, Erythropsis agilis, described by R. Hertwig. C. The phæodella are organs of nutrition of the Phæodaria and active in their metastasis ("Stoffwechsel"). Regarding them from this point of view, we may suppose that the phæodella are secreted products which serve for digestion, acting like the bile or the saliva of higher animals. Perhaps they too act like the venomous matter produced in the thread-capsules of the Acalephæ. The suggestion that they are mere excretions, or half-digested matters, as Hertwig supposes ("halb assimilirte Nahrungs-bestandtheile," 1879, loc. cit., p. 99) seems less probable. The most important fact illustrating their high signification for the processes of nutrition, digestion and for effecting changes on matter, seems to be the close relation of the phæodium to the astropyle; the radiate operculum of the latter, and the proboscis arising from it, being constantly covered and completely hidden by the central main mass of the phæodium.

The skeleton of the Phæodaria is always extracapsular, and exhibits in the majority of this legion such a characteristic shape, form, and structure, that these organisms may be easily recognised by it, even apart from the central capsule and the phæodium. In a few cases, however, the skeleton is so similar to that of some Nassellaria and Spumellaria, that it may be accidentally confounded with it. In general the skeleton of the Phæodaria is much larger, and much more highly developed, than that of most other Radiolaria, and exhibits the most wonderful appearances, and the most marvellous complications, which are found in the whole world of Protists, or of unicellular organisms. The varied composition and differentiation of the skeleton alone distinguishes the numerous families, genera, and species of Phæodaria described in the sequel; all the fifteen families, however, agree so completely in the structure of the central capsule and the phæodium described, that we may derive them all phylogenetically from a small skeletonless family, the Phæodinida.

The chemical composition of the skeleton seems to be, in the majority of Phæodaria, somewhat different from that of the other Radiolaria. In a few groups only, especially in the Cannobelida (Dictyocha, Mesocena, &c.), and in a part of the Castanellida and Concharida, the substance of the skeleton seems to be of pure silica, as in the Nassellaria and Spumellaria; these flinty skeletons, therefore, may be also found fossil. In the majority of Phæodaria, however, the skeleton does not consist of pure silica, but of an organic silicate; it becomes more or less intensely stained by carmine, and browned or blacked by fire; in many cases it even becomes completely burned and destroyed by the prolonged action of heat. This circumstance explains why Phæodaria in general are rare in deep-sea deposits, as in the common Radiolarian ooze of the Pacific, and why they are generally absent in fossil deposits. Even the pure Radiolarian rocks of the Barbados, &c., contain only a few Phæodaria, mainly Dictyochida.

According to the different forms of the skeleton, we may divide the legion or subclass of Phæodaria into two sublegions, four orders, and fifteen families. Firstly, we may distinguish as two groups the Phæocystina, without a lattice-shell, and the Phæocoscina, with a lattice-shell (compare above, p. [5]). The Phæocystina comprise three different families, viz., (1) Phæodinida, without any skeleton (Pl. [101], figs. 1, 2); (2) Cannorrhaphida, with an incomplete skeleton, composed of numerous separate, not radial pieces, which are scattered around the capsule in the calymma (Pl. [101], figs. 3-14; Pl. [114], figs. 7-13), and (3) Aulacanthida (Pl. [102]-[105]), with an incomplete skeleton, composed of numerous hollow radial tubes, which pierce the calymma and come in contact by their proximal ends with the surface of the central capsule.

The Phæocoscina, or the Phæodaria with a lattice-shell (embracing the great majority of the whole legion) exhibit three principal differences in the shape of their shell, and from these we distinguish the three following orders; (A) Phæosphæria, with a spherical, not bivalved shell (rarely of an ellipsoidal or lenticular, or another modified form), without a shell-mouth or a peculiar constant large opening on the lattice-shell; (B) Phæogromia, with an ovate or polyhedral, not bivalved shell (often also of a subspherical, ellipsoidal, or another modified form), constantly provided with a shell-mouth or a peculiar large opening on one pole of the main axis of the lattice-shell; (C) Phæoconchia, with a bivalved shell, composed of two completely separated, hemispherical, cap-shaped or boat-shaped valves (a dorsal and a ventral), comparable to that of the Brachiopoda.

The Phæosphæria, or those Phæodaria the big shell of which is usually spherical, never bivalved and never provided with a peculiar shell-mouth, comprise a great number of common and large-sized Phæodaria, which may be arranged into four different families, according to the different structure of the shell—(1) Orosphærida (Pl. [106], [107]), spherical shell extremely big and robust, composed of single piece of coarse lattice-work, the thick bars of which are stratified and contain partly a fine axial-canal, meshes of the network usually irregularly polygonal, no astral septa in the nodal points; (2) Sagosphærida (Pl. [108]), spherical shell large-sized, but extremely delicate and fragile, composed of a single piece of arachnoidal lattice-work, the thin bars of which are simple solid threads, without axial-canal, meshes of the network always large and triangular, no astral septa in the nodal points; (3) Aulosphærida (Pl. [109]-[111]), spherical shell large-sized, but very fragile, composed of numerous hollow cylindrical tubes, which are connected (and at the same time separated) by peculiar astral septa in the nodal points, meshes either triangular or polygonal; (4) Cannosphærida (Pl. [112]), spherical shell double, composed of two concentric shells which are connected by thin hollow radial tubes, the inner shell simple, solid or fenestrated, with a shell-mouth on the basal pole, the outer shell composed of hollow cylindrical tubes which are connected by astral septa in the nodal points. The structure of this outer shell is the same as in the Aulosphærida, while the basal mouth of the inner shell brings this family in closer relationship to the Phæogromia.

The Phæogromia, or those Phæodaria the shell of which is not bivalved, but provided with a peculiar constant mouth on the oral pole of the main axis, are in general similar to the Nassellaria (Monocyrtida), and may be divided into five different families, viz., (1) Challengerida (Pl. [99]), shell ovate or subspherical, also often triangular or lenticular, distinguished by a peculiar diatomaceous structure, an exceedingly fine tracery of regular hexagonal, very delicate network; (2) Medusettida (Pl. [118]-[120]), shell ovate, campanulate or cap-shaped, distinguished by a peculiar alveolar structure, with a corona of peculiar hollow, large, articulated feet around the mouth; (3) Castanellida (Pl. [113]), shell spherical or subspherical, of ordinary simple lattice-work, usually with a corona of simple solid teeth around the mouth; (4) Circoporida (Pl. [114]-[117]), shell spherical or polyhedral, with panelled or dimpled surface, distinguished by a peculiar porcellanous structure (numerous thin needles being embedded in a punctulate cement-substance), with hollow radial spines and with a corona of simple solid teeth around the mouth; (5) Tuscarorida (Pl. [100]), shell ovate or subspherical, with smooth surface, of the same peculiar porcellanous structure as the Circoporida, but with hollow, very long tubular teeth around the mouth.

The Phæoconchia are the peculiar and most interesting "Phæodaria bivalva," differing from all other Phæodaria, and from all known Radiolaria in general, in the possession of a bivalved lattice-shell, composed of a dorsal and a ventral valve. They may be divided into three families: (1) Concharida (Pl. [123]-[125]), shell with two thick and firm, regularly latticed valves, which bear no hollow tubes and no cupola or galea on their apex or sagittal pole; (2) Cœlodendrida (Pl. [121]), shell with two thin and fragile, scarcely latticed valves, which bear a conical cupola or a helmet-shaped galea on their apex, and hollow branched tubes arising from it (without rhinocanna and frenula); (3) Cœlographida (Pl. [122], [126]-[128]), shell with two thin and fragile, scarcely latticed valves, similar to those of the Cœlodendrida, but differing from them in the development of a peculiar rhinocanna or nasal tube upon each valve; this tube is connected by an odd or paired frenulum with the apex of the galea, and both together contain the phæodium.

The phylogenetic affinity of the fifteen families enumerated, and the morphological relationship based upon it, form a very difficult problem. The whole legion of Phæodaria is probably monophyletic, in as much as all the families may be derived from a single ancestral group, the skeletonless Phæodinida (Phæodina and Phæocolla); but at the same time polyphyletic, in as much as probably many families have been derived, independently one from another, from different branches of Phæodinida; or in other words, the characteristic malacoma of the Phæodaria (the cannopylean central capsule and the calymma with the phæodium) may be a monophyletic product, inherited from a single ancestral form; the manifold skeleton, however, is certainly a polyphyletic product, originating from different skeletonless Phæodinida.

Among the independent families of Phæodaria, derived directly from skeletonless Phæodinida by production of a peculiar skeleton, may be the following: Cannorrhaphida (Pl. [101], probably polyphyletic), Aulacanthida (Pl. [102]-[105]), Castanellida (Pl. [113]), Challengerida (Pl. [99]), Concharida (Pl. [123]-[125]), Circoporida (Pl. [114]-[117]) and Tuscarorida (Pl. [100]). The four families of Phæosphæria (the Orosphærida, Sagosphærida, Aulosphærida and Cannosphærida (Pl. [106]-[112]), may be derived perhaps from the Castanellida; and the Medusettida (Pl. [118]-[120]), have been perhaps derived from the Challengerida. The complicated affinities of these groups are however difficult to explain. The Cœlodendrida (Pl. [121]) are probably derived from the Concharida, and the Cœlographida (Pl. [126]-[128]) from the Cœlodendrida.

The geometrical fundamental form of the shell is in the majority of Phæodaria monaxonial, corresponding to the main axis of the enclosed central capsule; the astropyle of the latter, placed on the oral pole of the main axis, corresponds to the mouth of the shell in all Phæogromia. In the Phæosphæria, where no peculiar shell mouth is developed, the general fundamental form of the shell is usually homaxonial or spherical, often an endospherical polyhedron, rarely ellipsoidal or spindle-shaped (with prolonged main axis), or lenticular (with shortened main axis). The bivalved Phæoconchia have usually either an amphithect shell (with the same fundamental form as the Ctenophora), or a dipleuric, bilaterally symmetrical shell (with a dorsal and a ventral valve, a right and a left parapyle). A small number of Phæodaria (mainly Circoporida) are remarkable on account of the regular polyhedral form of their shell, the geometrical axes of which resemble crystalline axes and are defined by regular radial tubes; as the octahedral Circoporus (Pl. [117], fig. 6), the dodecahedral Circorrhegma (fig. 2), and the icosahedral Circogonia (fig. 1).

The siliceous or silicate bars, which compose the skeleton of the Phæodaria, are in the majority hollow tubes, filled up by jelly; in some other families, however, they are solid rods, as in the Nassellaria and Spumellaria. Such usual lattice-work, composed of solid rods, occurs only in the families Sagosphærida (Pl. [108]), Castanellida (Pl. [113]), and Concharida (Pls. [123]-[125]). A quite peculiar structure, a diatomaceous tracery of extremely fine and regular hexagonal frames, distinguishes the Challengerida (Pl. [99]). The hollow cylindrical tubes, which are found in the other families, appear in three different forms, simple, articulate, and provided with an axial thread. Simple hollow tubes, which are neither articulate nor provided with an axial thread, occur in the Cannorrhaphida (Pl. [101]), Aulacanthida (Pl. [102]-[105]), Cœlodendrida (Pl. [121], [122]), and Cœlographida (Pl. [126]-[128]). In all these families the hollow cylindrical tubes have a very thin wall and contain a wide cavity, filled only by jelly. The Orosphærida (Pl. [106], [107]), differ in the reduction of the cavity, which becomes very narrow (often rudimentary or lost), whilst the walls of the tubes become extremely thickened and stratified, numerous concentric layers of silica being disposed one over the other. The hollow cylindrical tubes contain an axial filament, or a thin thread of silica, placed in its axis, in the families Aulosphærida (Pl. [109]-[111]), Cannosphærida (Pl. [112]), Circoporida (Pl. [114]-[117]), and Tuscarorida (Pl. [100]). Usually the axial filament is connected with the thin wall of the tube by numerous horizontal branches. A quite peculiar structure distinguishes the Medusettida (Pl. [118]-[120]); their hollow tubes, extremely prolonged, are articulate owing to the presence of numerous, regular, equidistant transverse septa; these are pierced by a short tubule, similar to the siphon of the shells of Nautilus; this remarkable alveolar structure also occurs in the peripheral part of their shell-wall (and sometimes in the whole shell), numerous small polyhedral chambers or alveoles which communicate by small openings, being developed; they become easily filled with air in the dry shell (Pl. [120], figs. 11-16).

The substance of the siliceous or silicated shell-wall is, in the majority of Phæodaria, homogeneous and structureless, as in the Spumellaria and Nassellaria; but sometimes it acquires a peculiar structure. The thickened wall of the hollow tubes in the Orosphærida and in several Aulacanthida (Pl. [105], figs. 6-10) becomes distinctly stratified, concentric strata being disposed one over the other. A very remarkable structure, differing from that in all other Radiolaria, is found in the porcellanous shell of the Circoporida (Pl. [114]-[117]), and Tuscarorida (Pl. [100]). The thickened wall of the opaque shell is here composed of a peculiar silicated cement, which encloses numerous very thin and irregularly scattered needles (Pl. [115], figs. 6-9; Pl. [116], fig. 3). Dry fragments of these shells, observed by a strong lens, appear finely punctulate, and probably air, entering into these fine porules of the cement, causes the white colour and the calcareous or porcellanous appearance of the opaque dry shell. Its surface is smooth in the Tuscarorida (Pl. [100]), panelled in the Circoporida (Pl. [114]-[117]).

The hollow or solid spines, which arise from the shell of the Phæodaria, exhibit an extraordinary variety and elegance in the production of different branches, bristles, hairs, secondary spine, and thorns, hooks, anchor-threads, pencils, spathillæ, &c. These appendages are developed similarly to those of many Spumellaria, but exhibit a far greater variety and richness in form. They are organs partly for protection, partly for retention of food. They are much more interesting than in other Radiolaria.

Synopsis of the Orders and Families of Phæodaria.

I. Order PHÆOCYSTINA.

Skeleton absent or incomplete, composed of numerous single scattered pieces, without connection. Central capsule placed in the centre of the calymma.

Skeleton completely absent,1. Phæodinida.
Skeleton composed of numerous scattered pieces, not of radial tubes,2. Cannorrhaphida.
Skeleton composed of numerous hollow radial tubes, the proximal ends of which are in contact with the central capsule,3. Aulacanthida.

II. Order PHÆOSPHÆRIA.

Skeleton a simple or double lattice-shell, not bivalved, without a peculiar shell-mouth (shell usually spherical, rarely of a modified form, always without peristome). Central capsule placed in the centre of the shell-cavity.

Shell composed of a simple non-articulated lattice-plate, without astral septa in the nodal points.Network very robust and coarse, with irregular polygonal meshes; bars very thick, partly hollow,4. Orosphærida.
Network very delicate and fragile, with subregular, triangular meshes; rods very thin, filiform, always solid,5. Sagosphærida.
Shell composed of numerous hollow, tangential cylindrical tubes, which are separated by astral septa in the nodal points.Shell articulated, with astral septa, without a simple central shell,6. Aulosphærida.
Shell double, composed of two concentric shells; the outer articulated, the inner simple,7. Cannosphærida.

III. Order PHÆOGROMIA.

Skeleton a simple lattice-shell, not bivalved, constantly provided with a peculiar large shell-mouth placed on the oral pole of the main axis; peristome usually surrounded by peculiar feet or teeth. (Shell either spherical or ovate, or of another form). Central capsule excentric, placed in the aboral half of the shell-cavity.

Structure of the shell not porcellanous (without needles imbedded in a punctulate cement-substance).Structure of the shell diatomaceous, with very delicate and regular hexagonal pores. No articulate feet,8. Challengerida.
Structure of the shell alveolar, with hollow alveoles between a double plate. A corona of articulated feet around the mouth,9. Medusettida.
Structure of the shell of simple lattice-work, neither diatomaceous nor alveolar. No articulate feet,10. Castanellida.
Structure of the shell porcellanous, with peculiar fine needles imbedded in a punctulate cement-substance (a circle of pores around the base of each tube).Surface of the shell panelled or dimpled (spherical or polyhedral). Peristome flat,11. Circoporida.
Surface of the shell smooth, even (ovate or subspherical). Peristome prominent,12. Tuscarorida.

IV. Order PHÆOCONCHIA.

Skeleton a bivalved lattice-shell, composed of a dorsal and a ventral valve which are completely separated (rarely connected by a ligament on the aboral pole). Central capsule enclosed between the two valves.

The two valves of the bivalved shell thick and firm, regularly latticed, without a galea or cupola on their apex, and without hollow tubes,13. Concharida.
The two valves of the bivalved shell very thin and fragile, scarcely latticed, each with a conical cupola or a helmet-shaped galea on its sagittal pole or apex, and with hollow tubes.Galea without rhinocanna or nasal tube, without frenula,14. Cœlodendrida.
Galea with a rhinocanna or nasal tube, both connected by an odd or paired frenulum,15. Cœlographida.

I. Order PHÆOCYSTINA.

Skeleton absent or incomplete, composed of numerous single scattered pieces, without connection. Central capsule placed in the centre of the calymma.

Skeleton completely absent,
1. Phæodinida.
Skeleton composed of numerous scattered pieces, not of radial tubes,
2. Cannorrhaphida.
Skeleton composed of numerous hollow radial tubes, the proximal ends of which are in contact with the central capsule,
3. Aulacanthida.

II. Order PHÆOSPHÆRIA.

Skeleton a simple or double lattice-shell, not bivalved, without a peculiar shell-mouth (shell usually spherical, rarely of a modified form, always without peristome). Central capsule placed in the centre of the shell-cavity.

Shell composed of a simple non-articulated lattice-plate, without astral septa in the nodal points.
Network very robust and coarse, with irregular polygonal meshes; bars very thick, partly hollow,
4. Orosphærida.
Network very delicate and fragile, with subregular, triangular meshes; rods very thin, filiform, always solid,
5. Sagosphærida.
Shell composed of numerous hollow, tangential cylindrical tubes, which are separated by astral septa in the nodal points.
Shell articulated, with astral septa, without a simple central shell,
6. Aulosphærida.
Shell double, composed of two concentric shells; the outer articulated, the inner simple,
7. Cannosphærida.

III. Order PHÆOGROMIA.

Skeleton a simple lattice-shell, not bivalved, constantly provided with a peculiar large shell-mouth placed on the oral pole of the main axis; peristome usually surrounded by peculiar feet or teeth. (Shell either spherical or ovate, or of another form). Central capsule excentric, placed in the aboral half of the shell-cavity.

Structure of the shell not porcellanous (without needles imbedded in a punctulate cement-substance).
Structure of the shell diatomaceous, with very delicate and regular hexagonal pores. No articulate feet,
8. Challengerida.
Structure of the shell alveolar, with hollow alveoles between a double plate. A corona of articulated feet around the mouth,
9. Medusettida.
Structure of the shell of simple lattice-work, neither diatomaceous nor alveolar. No articulate feet,
10. Castanellida.
Structure of the shell porcellanous, with peculiar fine needles imbedded in a punctulate cement-substance (a circle of pores around the base of each tube).
Surface of the shell panelled or dimpled (spherical or polyhedral). Peristome flat,
11. Circoporida.
Surface of the shell smooth, even (ovate or subspherical). Peristome prominent,
12. Tuscarorida.

IV. Order PHÆOCONCHIA.

Skeleton a bivalved lattice-shell, composed of a dorsal and a ventral valve which are completely separated (rarely connected by a ligament on the aboral pole). Central capsule enclosed between the two valves.

The two valves of the bivalved shell thick and firm, regularly latticed, without a galea or cupola on their apex, and without hollow tubes,
13. Concharida.
The two valves of the bivalved shell very thin and fragile, scarcely latticed, each with a conical cupola or a helmet-shaped galea on its sagittal pole or apex, and with hollow tubes.
Galea without rhinocanna or nasal tube, without frenula,
14. Cœlodendrida.
Galea with a rhinocanna or nasal tube, both connected by an odd or paired frenulum,
15. Cœlographida.