The common character which unites the three rather different subfamilies, the Cannobelida, Dictyochida and Catinulida into a single family, and which separates this family, the Cannorrhaphida, from the other Phæodaria, is to be found in the composition of the rudimentary skeleton from numerous single pieces, which are loosely scattered either on the surface of the calymma, or throughout its jelly-mass, and which are never arranged radially and never touch the central capsule as is always the case in the closely allied Aulacanthida.
The slender spicula of the Cannobelida are cylindrical or spindle-shaped, tubular, scattered in variable numbers, but always in a tangential direction on the surface of the calymma. Usually they are 0.2 to 0.5 long, and 0.005 to 0.03 broad; either straight or slightly curved; smooth and simple in Cannobelos, spiny or branched in Cannorrhaphis (Pl. [101], figs. 3-5). Their wall is thin and fragile, their diameter sometimes equal throughout their whole length, at other times tapering towards both ends. Their cavity is filled by jelly, and seems to be open at both ends, since the purified and dried spicula constantly become filled by air.
The peculiar pieces of silica which compose the skeleton of the Catinulida are not hollow, like the rods of the other Cannorrhaphida, but concave hemispherical cups or more flatly vaulted little dishes, the thin flinty wall of which is slightly thickened at the circular margin, and radially striped above it. In all three species of Catinulus observed they were scattered throughout the calymma in hundreds or thousands (Pl. [117], fig. 8). Their relation to the Dictyochida is doubtful. Perhaps the small cups of Catinulus may be derived from the simple rings of Mesocena, by development of an operculum on one side of the ring.
The skeleton of the Dictyochida is much more developed and possesses a higher morphological interest; the numerous different forms, however, which its pieces here assume, may be all derived from the simple circular ring of Mesocena. This ring is formed by a thin, hollow, cylindrical, or prismatic rod, sometimes circular or elliptical, at other times polygonal. From its margin small, hollow, radial spines often proceed (Pl. [101], fig. 9). In Dictyocha there arise from the ring two, three, four or more siliceous bars or arches, which form one or more bulges over one side of the ring; usually the little fenestrated shell thus produced assumes the form of a three-sided or four-sided pyramid, or of a little hat with three or four meshes (Pl. [101], figs. 10-14). From this Dictyocha (in a restricted sense) we separate the genus Distephanus, in which the little pyramids become truncated, so that one central apical mesh (the apical or upper ring) is surrounded by four, five, six or eight lateral meshes, the sides of the pyramid (Pl. [114], figs. 7-9). The edges of the small pyramid are formed by the same number of siliceous bars arising from the ring and alternating with the meshes. Radial spines in different numbers and arrangements arise from the corners of the two parallel rings, as well from the smaller apical as from the larger basal ring. The simple apical ring of Distephanus becomes divided or fenestrated in the highest developed genus of this subfamily, in Cannopilus (Pl. [114], figs. 10-13); each pileated piece of the skeleton exhibits here two rows of alternating lateral meshes, an upper row of smaller and a lower row of larger meshes.
The majority of Dictyochida are armed with spines or thorns, which arise in a regular manner from different points of the annular or pileated pieces. In the ancestral genus, Mesocena, radial spines start from the corners of the simple ring in centrifugal direction, and lie horizontally in its plane. As these primary corner-spines determine the radial composition of the more highly developed genera we call them perradial (lying in rays of the first order). In Dictyocha and Distephanus commonly (but not quite constantly) these perradial spines alternate with the ascending bars which bisect the sides of the basal ring; these bars are therefore interradial (lying in rays of the second order); consequently also the corners of the apical ring of Distephanus are interradial. The latter also often bear small thorns or teeth. Other teeth frequently start in centripetal direction from the lower or basal ring, on the side of the perradial spines, and frequently they are directed obliquely downwards.
In Dictyocha and Distephanus are frequently found remarkable twin pieces, composed of two pileated and reticulated skeleton pieces. These are united by their basal rings loosely in such a way that they form together a small fenestrated subspherical body; the union is strengthened by those small teeth of the basal rings, which are directed downwards and catch one into the other (Pl. [101], fig. 12; Pl. [114], fig. 8). A similar twin piece has been already observed by Stöhr in the fossil Distephanus rotundus, and upon this was founded this genus. Since the teeth of the two opposed basal rings, catching one into the other, seem to be specially adapted for the composition of those small double pyramids, it is probable that the latter possess a special protective function in these Phæodaria, and perhaps envelop their phæodella or their flagellate spores (?). In every case these formations are very remarkable.
The Central Capsule of the Cannorrhaphida seems to possess the same shape in the three subfamilies, and to agree in general with that of the Aulacanthida. In a living specimen of Dictyocha stapedia, which I observed at Ceylon (Pl. [101], fig. 10), the three openings of the Tripylea were distinct; the radiate operculum of the astropyle (on the oral pole) was surrounded by the granules of the dark phæodium, whilst on the opposite aboral side, two parapylæ or conical secondary openings were visible. The voluminous spherical calymma (about four times as broad as the central capsule) contained numerous large alveoles (as in Aulosphæra) and its surface was protected by numerous pileated pieces of the skeleton; the basal ring of the latter was placed tangentially in the spherical surface of the calymma, their apical spine being directed outwards. The pseudopodia, arising from the central capsule and forming a network between the alveoles of the calymma, radiated outwards in great number from its surface (Pl. [101], fig. 10).
The propagation by self-division seems to be very frequent in the Cannorrhaphida. I frequently found two equal central capsules in one calymma, as in the first observed species, Cannobelos cavispicula, and in Cannorrhaphis spinulosa (Pl. [101], fig. 3), sometimes also in Dictyocha and Distephanus. As already mentioned, Catinulus constantly exhibited four central capsules united in each calymma.
Synopsis of the Genera of Cannorrhaphida.
I. Subfamily Cannobelida. Pieces of the skeleton cylindrical or spindle-shaped tangential tubules. |  | Tubules simple, smooth, | 658. Cannobelos. | ||
| Tubules spiny or branched, | 659. Cannorrhaphis. | ||||
II. Subfamily Catinulida. Pieces of the skeleton hemispherical or cap-shaped, solid. | | Caps or hemispherical pieces of the skeleton solid, with radiate margin and circular opening, | 660. Catinulus. | ||
III. Subfamily Dictyochida. Pieces of the skeleton either simple rings or pileated or pyramidal bodies, composed of thin hollow rods and reticular meshes. |  | Flinty pieces simple or arched rings, not truncated pyramids, with a basal ring, but without apical ring. |  | Basal ring simple, not arched or fenestrated, | 661. Mesocena. |
| Basal ring fenestrated, with two or more arches, vaulted over one side, | 662. Dictyocha. | ||||
| Flinty pieces of the skeleton resembling a truncated pyramid, with an upper smaller apical ring, and a lower larger basal ring. |  | Apical ring simple, not fenestrated (one girdle of meshes on each piece), | 663. Distephanus. | ||
| Apical ring fenestrated (two girdles of meshes on each piece), | 664. Cannopilus. | ||||