A conchological manual

by G. B. Sowerby

CONVOLUTE. (Con, together; volvo, to revolve). This term can be strictly applied only to symmetrical shells, signifying that the volutions are parallel to each other in a horizontal direction, as in the Ammonites, &c.; but the term is also commonly used in describing such shells as Conus, in which, the direction of the whorls being scarcely oblique, the last whorl almost entirely covers those which precede it. This is the case with Lamarck's family of Enroulées. Fig. 440 to 462.

CORALLIOPHAGA. Bl. Cypricardia Coralliophaga, Lam.—Descr. Oval, elongated, finely striated from the apex to the base, cylindrical, equivalve, very inequilateral; umbones slightly raised and quite anterior; hinge nearly the same in both valves; two small cardinal teeth, one of which is bifid, placed before a kind of lammellated tooth, beneath a very slender external ligament; two small, distant, muscular impressions, united by a striated palleal impression, which is strongly striated posteriorly.—Obs. This shell, which is found in the empty holes of dead Lithodomi, in some instances conforming its shape to its situation, differs from Cypricardia of Lamarck, principally in its cylindrical form. C. Carditoidea, fig. 92. Mediterranean and East Indies.

CORBICULA. Megerle. Cyrena, Lam.

CORBIS. Cuv. (A basket.) Fam. Nymphacea, Lam.—Descr. Transverse, oval, thick, ventricose, equivalve, sub-equilateral, free, cancellated, with denticulated internal margins; hinge with two cardinal and two lateral teeth in each valve; of the latter, one near and one remote from the umbones; muscular impressions lunulate, two in each valve, united by an entire palleal impression, without a sinus.—Obs. This genus, of which only two or three recent species are known, resembles many species of Venus and Cytherea in general form; but differs in having lateral teeth, and in the palleal impressions which in all the Veneres, &c. is sinuated. From Lucina it may be known, not only by its oval form, but also by the muscular impressions, which, in Lucina are produced into an elongated point; it will also be distinguished from Tellina, by the want of a posterior fold in the valve, for which that genus is remarkable. C. Fimbriata, fig. 101, is an inhabitant of the Indian Ocean. Several fossil species are found in the recent formations, above the chalk, at Grignon and Hauteville.

CORBULA. Brug. (A little basket.) Fam. Corbulacea, Lam. Conchacea, Bl.—Descr. Inequivalve, sub-equilateral, transverse, gibbose, not gaping; cardinal tooth in each valve, conical, curved, prominent, inserting its extremity into a pit in the opposite hinge; cartilage attached to the tooth of the smaller valve, and the pit in the larger; muscular impressions, two in each valve, distant, rather irregular; palleal impression posteriorly angulated.—Obs. The shells composing this genus were placed in Mya by Linnæus, but differ from the true Myæ in having a sinus in the palleal impression, and a prominent ligamentiferous tooth in each valve, whereas the Myæ have but one. The Corbulæ are marine, some species inhabiting the British coasts. Fossil species occur abundantly in green sand, London clay, crag, and corresponding formations. Fig. 89. C. Nucleus.

CORBULACEA. (Corbulées, Lam.) A family of the order Conchifera Dimyaria, Lam., containing the genera—

1. Corbula, with a prominent curved tooth. The Fresh-water species has been separated under the name Potamomya. Fig. 89.

2. Pandora. Thin, pearly, no teeth. Fig. 90.

CORDIFORM. (Cor, a heart.) Heart-shaped, a term applied generally to any shell which may be fancied to resemble a heart in shape, as Isocardia, fig. 126, and Cardium Dionæum, fig. 122.

CORIACEOUS. (Corium, leather.) Of the substance of leather. Ex., the integument into which the valves of Chitones are inserted.

CORIOCELLA. Bl. The animal designated by this name is described by De Blainville as being without any traces of shell, either internal or external. This must have arisen from the imperfection of the specimen described, probably deprived by accident of its shell. The testaceous appendage of the Coriocella is now well known to naturalists. It is a milky white, transparent shell, shaped like Sigaretus.

CORNEA, and Pisum, Megerle. Cyclas, Lam.

CORNEO-CALCAREOUS. A term used to express the mixture of horny and shelly matter which enters into the composition of some shells, Aplysia, for instance. It is also applied to those Opercula, which are horny on one side, and testaceous on the other, as that of Turbo.

CORNEUS. Horny. A species of Patella has had the specific name corneus given to it, because its texture more nearly resembles that of a horn than that of a shell. The epidermis of fresh-water shells is of a similar composition.

CORNUCOPIA. Humph. Lepas, Linn.

CORONALES. See Coronular Multivalves.

CORONATED. (Corona, a crown.) Applied to shells when ornamented with a series of points, tubercles, &c., round the upper edges of the volutions. Ex. Conus Nocturnus, fig. 459.

CORONAXIS. One of the two genera into which Swainson divides the genus Conus, consisting of those species which have a row of tubercles on the upper edge of the whorls, an arrangement by which he would in many instances, not only separate between two individuals of the same species, but also between two parts of the same shell; for instances occur in which the earlier whorls are coronated, while the body whorl and the penultimate are perfectly plain.

CORONULA. (Corona, a crown, dim.) Order, Sessile Cirripedes, Lam. Fam. Balanidea, Bl.—Descr. Six radiated valves, joined side by side in a circle, forming a depressed cone; internal structure of the valves, porous or chambered; thickened at the base; operculum consisting of four valves in pairs; imbedded horizontally in a cartilaginous substance.—Obs. The shells composing this genus are found partly imbedded in the skin of whales, and the shells of tortoises, and are therefore destitute of the shelly foundation on which the Balani and other Coronular Multivalves are supported. C. Testudinaria, (Chelonobia, Leach,) fig. 15. C. Balænarum, (Cetopirus, Ranz.) fig. 16. C. Diadema, (Diadema, Ranz.) fig. 17.

CORONULAR MULTIVALVES are those which have their parietal valves joined together side by side in a circle, surrounding the body of the animal, so as to form a sort of coronet. This is the characteristic of the Sessile Cirripedes of Lamarck's system, the Balanidea of De Blainville.

CORRODED. (Corrodo, eat away, consume.) The umbones, apices, and other thick parts of shells, are frequently worn away or consumed by the action of the element in which they exist. As the thickest parts of some shells are the most subject to this operation, it appears to the author to arise from the outer surface of the shell, being less under the influence of the animal juices than the other parts; and therefore, more exposed to the influence of the surrounding element. This, however, is not the case with respect to the Nayades and other fresh-water shells; with these, corrosion does not take place until after the thick epidermis which covers them, becomes wounded by some means or other, and then the animal thickens its shell within as fast as it is corroded without.

CORTALUS. Montf. (Conch. Syst. 1. 115.) A genus of microscopic Foraminifera, placed by De Blainville in a division of the genus Rotalites.

COSTATED. Ribbed, as Cardium Angulatum, fig. 123.

COSTELLARIA. A sub-genus of the genus Tiara, Sw. (Mitra.) C. rigida. Swainson, Zool. Ill. 1st series, pl. 29.

COWRY. A common name for shells of the genus Cypræa.

CRANIA. (Cranium, a skull.) Fam. Rudistes, Lam. Order, Pallio-branchiata, Bl.—Descr. Inequivalve, equilateral, irregular, sub-quadrate; upper valve patelliform, conical, with the umbo near the centre; lower valve attached by its outer surface; muscular impressions, 4 in each valve; two large, posterior, distant; two small, near to each other, central. No hinge teeth; no ligament.—Obs. This genus properly belongs to the Brachiopoda, Lam. It differs from Orbicula in the mode of attachment, which in the latter, is by a byssus passing through the lower valve, and not by the valve itself. Hipponyx has only two muscular impressions in each valve. The name of this genus is derived from the inner surface of the attached valve, which presents a remarkable resemblance to the facial portion of a human skull. This appearance is caused by the situation and elevated edges of the muscular impressions. Fig. 197. Coasts of Britain and Mediterranean.

CRASSATED. (Crassus, thick.) Used to express a thickness in the substance of a shell. Ex. Glycimeris, fig. 67.

CRASSATELLA. Lam. (Crassus, thick.) Fam. Mactracea, Lam. Conchacea, Bl.—Descr. Equivalve, inequilateral, close, thick, rounded anteriorly, rostrated posteriorly, with denticulated margins, smooth, or ribbed transversely; hinge with a triangular pit containing the cartilage, two anterior cardinal teeth, and a posterior depression in one valve; one anterior tooth and a slight anterior marginal elevation, and a posterior elevation in the other valve. Muscular impressions distant, strongly marked. Palleal impression not sinuated.—Obs. The few recent species known are marine, several being brought from the coasts of New Holland. Fossil species are found in Calcaire-grossier and London clay. The Crassatella are known from the Veneres, &c., by the ligamentary pit in the hinge, and from Lutraria and Mactra by the thickness and closeness of the shell. Fig. 84, C. rostrata.

CRASSINA. Lam. Astarte, Sow.

CRASSIPEDES. Lam. (Crassus, thick; pes, foot.) The first section of the order Conchifera Dimyaria, Lam. In this section the foot of the animal is thick, and the shell gapes considerably. It is divided into the families Tubicolæ, Pholadidæ, Solenidæ, and Myaria. Fig. 44 to 76.

CRASSISPIRA. Sw. A genus separated from Columbella, Auct. for which Mr. Swainson quotes "Pleurotoma Bottæ, Auct." Crassispira fasciata, Sw. Lardn. Cyclop. Malac. p. 313.

CRENATED. (Crena, a notch.) Applied to small notches, not sufficiently raised or defined, to be compared to teeth. Ex. The hinge of Iridina, fig. 150.

CRENATULA. Lam. Fam. Malleacea, Lam. Margaritacea, Bl.—Descr. Compressed, foliated, irregular, sub-equivalve, inequilateral, oblique; umbones terminal; hinge linear, nearly straight, with a series of excavations, containing the cartilage, while the intervening ridges are covered with the ligament, properly so called. Muscular impression oblong, indistinct.—Obs. This genus is known from Perna by the hinge, which in the latter is composed of a series of regular, straight, ligamentary grooves placed across it. In Crenatula also there is no passage for the byssus, as in Perna. C. Mytiloides, fig. 168. Coasts of the Red Sea.

CRENULATED. Finely crenated or notched.

CREPIDULA. Lam. (Crepidula, a little slipper.) Fam. Calyptracea, Lam. and Bl.—Descr. Oval, irregular, patelliform; apex lateral, incurved, or sub-spiral; external surface convex, smooth, ribbed, waved, or covered with spines; interior concave, smooth, with a flattish septum reaching nearly half across the cavity; epidermis light brown.—Obs. The difference between this genus and Calyptræa is that in the latter, the septum is more free from the sides of the shell, so that, instead of forming a regular plate, covering half the aperture, it assumes a variety of shapes, and in some is cup-shaped, in others forked, and in some forms a little angular shelf. Indeed, the variations are so numerous that I think it would be better to throw the two genera into one, and then divide them into smaller groups. Some species of Calyptræa are farther removed from each other with respect to the characters of the septum and general form of the shell, than they are from the Crepidulæ. Fig. 239. Mediterranean, North and South America, East and West Indies, New South Wales, &c.

CREPIDULINA. Bl. Cristellaria, Lam. Microscopic.

CRESEIS. Ranz. Order, Pteropoda, Lam.—Descr. Thin, fragile, transparent, pyramidal, pointed; with a dorsal ridge produced into a point at the edge of the aperture.—Obs. The species found in the Mediterranean is named C. Spinifera (fig. 222), from its resemblance to a thorn.

CREUSIA. Leach. (Creux, se. Fr. a cavity.) Fam. Balanidea, Bl. Order, Sessile Cirripedes, Lam.—Descr. A depressed cone, consisting of four valves, supported upon, and jointed to, a cup-shaped cavity formed in the Madrepores, in which it resides. Aperture quadrilateral, closed by an operculum of four valves.—Obs. This genus is distinguished from Pyrgoma, which is supported on the edge of a similar cup-shaped cavity, by the paries being composed of four valves, whereas in Pyrgoma, it consists of a single piece. Fig. 28, C. Gregaria. East Indies.

CRICOSTOMATA. Bl. The second family of Asiphonibranchiata, Bl. It is thus described: "shell equally (with the animal) variable in general form, but of which the aperture, always nearly round, is completely closed by the shelly or horny operculum; whorls few, and apex sublateral." This family agrees in some measure with the family Turbinacea of Lamarck, and with the genus Turbo in the system of Linnæus. It contains the genera Pleurotomaria, Delphinula, Turritella, Proto, Scalaria, Vermetus, Siliquaria, Magilus, Valvata, Cyclostoma, and Paludina.

CRIOCERATITES. A genus composed of species of Ammonites, with disconnected whorls. C. Duvallii, fig. 482.

CRIOPUS. Poli. Crania, Auct.

CRISTACEA. Lam. The third family of Polythalamous Cephalopoda, Lam. This family is described as including shells of the following characters:—"Multilocular, flattened, nearly reniform; the chambers gradually increasing in length, as they approach the outer arched margin, and appearing to revolve round an eccentric, more or less marginal axis. The Cristacea contain the genera Renulina, Cristellaria, and Orbiculina."

CRISTACEA. Bl. The third family of Polythalamia, Bl. containing the genera Crepidulina, (Cristellaria, Lam.) Oreas and Linthuris.

CRISTARIA. Schum. Dipsas Plicatus, Leach. Anodon tuberculatus, Fer.

CRISTELLARIA. Lam. Crepidulina, Bl. Fam. Cristacea, Lam. and Bl.—Descr. Semidiscoidal, chambered; whorls contiguous, enlarging progressively; spire eccentric, sublateral; septa imperforate. Microscopic.

CRYPTA. Humph. Crepidula, Lam.

CRYPTELLA. Webb. (Κρυπτω, to conceal.) Testacellus Ambiguus of Ferrusac. Published in Sowerby's Genera of Shells as Parmacella calyculata.—Descr. A small patelliform shell, with a very short papillary spire; and the aperture irregularly expanded. Fig. 256. Canary Islands.

CRYPTOCONCHUS. Bl. A genus composed of species of Chiton, the valves of which are covered by the integument, as Chiton porosus of Burrows. Ch. amiculatus of Pallas.

CRYPTODIBRANCHIATA. Bl. The first order of the class Cephalophora, Bl. containing families of molluscous animals destitute of shells.

CRYPTOSTOMA. Bl. Differs from Sigaretus, Lam. principally in the soft parts of the animal. De Blainville remarks that he is acquainted with only two species (from the Indies), which he can with decision refer to the genus, but he thinks that many of the Lamarckian Sigareti may very probably be found to belong to it, as soon as the soft parts shall be known. The species which he figures is Cryptostoma Leachii. (Manuel de Malacologie, pl. 42. fig. 3.)

CTENOCONCHA. Gray. Described as having many characters in common with the Solens, the teeth like Nucula, but the cartilage entirely external. Solenella, Sow.?

CUCULLÆA. Lam. (Cucullus, a hood.) Fam. Arcacea, Lam.—Descr. Sub-quadrate, nearly equivalve, sub-equilateral, deep; hinge rectilinear, with a series of angular teeth, small near the umbones, larger and more oblique towards the extremities; umbones separated by a flat external area, on which the ligament is spread. Anterior muscular impression produced into a sharp-edged plate or ledge, projecting from the side of the shell. Posterior muscular impression flat and indistinct.—Obs. This genus very much resembles Arca in general form, but differs in the oblique, lengthened character of the remote teeth, and in the singularly prominent edge of the muscular impression. China. Fig. 133, C. Auriculifera.

CUCUMIS. Klein. Marginella, Auct.

CULTELLUS. Species of Lutraria, Lam. which have the umbones placed near the extremity of the shell. Ex. L. Solenoides, fig. 78.

CUMA. Humph. Fusus and Fasciolaria, Lam.

CUMINGIA. Sow. Fam. Mactracea, Lam.—Descr. Equivalve, inequilateral, transverse, rounded anteriorly, subrostrated posteriorly. Hinge with a central spoon-shaped cavity in each valve, containing the cartilage; a very small anterior cardinal tooth in each valve; two lateral teeth in one valve, none in the other: muscular impressions two in each valve, distant; palleal impression with a very large posterior sinus.—Obs. The species known at present are found in sand, in the fissures of rocks in Tropical climates. They resemble Erycina in general form and character, but differ in having the internal cartilage placed in a prominent spoon-shaped process, while that of Erycina is contained in a hollow which sinks under the umbones. This genus should be placed near Amphidesma. Cumingia mutica, fig. 87.

CUNEIFORM. (Cuneus, a wedge.) Wedge-shaped, as Donax, fig. 108.

CUNEUS. Megerle. Venus Meroe, Linn. and similar species.

CUNICULA. Sw. A sub-genus of Uniones, thus described:—"Ovate, oblong; bosses thick, but depressed; cardinal teeth moderate. C. planulata, patula, rubiginosa, secura, purpurascens."

CURVED. Arched or bent. Ex. Dentalium, fig. 2.

CURVULA. Rafinesque. A fossil imperfectly described as differing from Pinna, in being inequivalve.

CUVIERIA. Ranz. (Baron Cuvier.) Class, Pteropoda, Lam.—Descr. Thin, transparent, glassy, cylindrical, rounded and inflated at the closed extremity, compressed towards the opening, so as to render it oval. This genus differs from Vaginula in being rounded, instead of pointed, at the lower extremity. Mediterranean. Fig. 223, C. Columella.

CYCLAS. Brug. Fam. Conques Fluviatiles, Lam. Conchacea, Bl.—Descr. Orbicular, thin, subovate, ventricose, sub-equilateral, equivalve; cardinal teeth minute, one more or less complicated in the left valve, two diverging in the right; lateral teeth elongated, compressed, laminar, acute, doubled in the left valve; ligament external; epidermis thin, horny.—Obs. The Cyclades are viviparous, and abound in ditches, ponds, slow streams, &c. in Europe and North America. The genus Pisidium has been separated on account of a difference in the animal, and may be known from Cyclas by being less equilateral, and the anterior side being the longest. Fig. 111, C. Rivicola.

CYCLOBRANCHIATA. Bl. The third order of the second section of Paracephalophora Monoica, Bl. containing no genera of Testaceous Mollusca.

CYCLOCANTHA. Sw. A genus of "Trochidæ," consisting of Turbo stellaris and T. Calcar, and corresponding with the genus Calcar, Montf.

CYCLONASSA. Sw. A genus of "Nassinæ," Sw. consisting of Nassa Neritoidea, and corresponding with the genus Cyclops, Montf.

CYCLOPHORUS. Montf. A generic name proposed for those species of Cyclostoma, Auct. which have an umbilicus. C. Involvulus, fig. 304, would be the type of this genus.

CYCLOPS. Montf. Nassa Neritoidea, Auct. fig. 424.

CYCLOSTOMA. Auct. (κυκλος, cyclos, round; στομα, stoma, mouth.) Fam. Colimacea, Lam. Cricostomata, Bl. A genus of land shells varying in shape from that of Pupa to that of a flat orb; the aperture is generally circular and the peritreme uninterrupted, thickened and sometimes reflected, the operculum is shelly and spiral. Two other genera of land shells are provided with opercula, and consequently might be confounded with this genus. In Helicina, the operculum is concentric and the peritreme is not continuous; while in the small genus hitherto almost unknown of Pupina, the peritreme is not continuous and there is a glassy enamel over the whole of the external surface. In the plates we have represented, C. ferrugineum, fig. 303; C. involvulus, fig. 304.

CYCLOTUS. Guild. A sub-genus of Cyclostoma, consisting of those species which are discoidal, as C. Planorbulum. Fig. 530.

CYLINDER. Montf. Conus textile, Auct. (fig. 461) and other species having a cylindrical form.

CYLINDRELLA. Sw. A genus of the family "Ovulinæ," Sw. composed of cylindrical species of Ovulum? The wood-cut illustrating this genus has the appearance of a Bulla.

CYLINDRICAL. (κυλινδρος, a cylinder.) This like other mathematical terms is used with great latitude by Conchologists, and applied to any shell the sides of which are nearly parallel, with the extremities either rounded, flat, or conical. Ex. Oliva, fig. 457.

CYLLENE. Gray. Fam. Purpurifera, Lam.—Descr. Oval, thick, with a short acute spire; an oval aperture terminating anteriorly in a slight emargination, posteriorly in a short canal; a fold at the lower end of the body whorl; outer lip thick, striated within; angle of the whorls tuberculated.—Obs. This genus of small marine shells resembles Voluta in general character, but differs in having a smooth columella without folds. Recent, Pacific Ocean; Fosil, London clay. Fig. 425.

CYMBA. Brod. (Cymba, a boat or skiff.) Fam. Columellaria, Lam.—Descr. Smooth, ventricose, with a very short, mammillated, rude spire; and a very large, wide aperture, terminated anteriorly in a deep emargination; posteriorly in a flat ledge, which separates the outer lip from the body whorl; columella with three or four oblique, laminar, projecting folds, terminating in a point; outer lip thin, with its edge sharp; epidermis smooth, brown, covered partly or entirely by the glassy enamel, which, commencing with the outer lip, spreads over the body of the shell.—Obs. These very elegant shells, found in Africa, are distinguished from the true Volutes by the shapeless, mammillated apex of the short spire, by the large size of the aperture, and by the horizontal ledge which separates the outer lip from the body whorl. The genus Melo, also separated by Mr. Broderip from the Volutes, agrees with Cymba in some respects, but differs in the regularity of the spire. Fig. 434, C. Porcina.

CYMBIOLA. Sw. The generic name for a group of Volutes, described as "armed with spinous tubercules, sometimes smooth, but never ribbed; spiral whorls gradually diminishing in size, but not distorted; apex thick and obtuse; pillar with four plaits." Mr. Swainson remarks that this genus is chiefly distinguished by the obtuse, but not irregular spire. The typical species are stated to be V. Rutila and V. Vespertilio, fig. 433. Tropical.

CYMBULIA. (Dim. from Cymba.) Fam. Pteropoda, Lam. An extremely light, cartilaginous covering of a molluscous animal, so named from its similarity in shape to a boat. We mention it here on account of its similarity to the shelly or glassy covering of other Pteropods, to which, although membranaceous, it is evidently analogous. The Cymbuliæ are found in the Mediterranean.

CYPRÆA. Auct. Fam. Enroulées, Lam. Angyostomata, Bl.—Descr. Oval or oblong, ventricose, convolute, covered by an enamel, generally smooth and shining. Spire short, nearly hid. Aperture long, narrow, terminating in a short canal at both extremities. Outer lip dentated, thickened, inflected. Inner lip dentated, thickened, reflected over part of the body whorl.—Obs. These shells are so distinguished by the two rows of teeth arranged on each side of the aperture; the thickened front formed by the inner and outer lips; and the enamel deposited over the back of the shell from the mantle of the animal which envelopes it, that there is no danger of confounding them with any other genus, except in a young state. Before they have arrived at the full growth, the front is not thickened, and the outer lip is thin, not inflected, nor are the teeth formed. In this state the shell resembles, in some degree, an Oliva. Some species are striated, ribbed, or tuberculated, but the generality are smooth. Most species belong to tropical climates, only one to Great Britain. The C. Moneta is current as money in some parts of Africa, and many species are worn as ornaments by the South Sea Islanders. The colouring in most species is exceedingly rich, and arranged in every variety of spots, patches, rings, lines, bands and clouds. The species most esteemed by collectors are C. Mappa, C. Testudinaria, C. Pustulata, C. Aurora, C. Princeps, of which only two specimens are known, C. Leucodon, &c. See also Cypræovulum, Trivea and Luponia. The fossil species are principally from the Calc-grossier, the London Clay, Crag, &c. Fig. 445 to 450. The latest revision of this genus has been effected by Mr. G. B. Sowerby, sen., who has published a complete catalogue in his son's Conchological Illustrations. This catalogue enumerates 130 species, the whole of which are figured in parts 1 to 8, 101 to 131 of the above mentioned work.

CYPRÆCASSIS. Stutch. (Cypræa and Cassis.)—Descr. Shell, when young, striated, reticulated, or tuberculated; outer lip simple: when mature, outer lip involute and toothed; columellar lip also toothed; aperture straight, anteriorly terminated by a recurved canal, posteriorly by a shallow channel. Animal with the mantle bilobed; operculum none.—Obs. The reasons given for separating this genus from Cassis, are, 1st, That the shells of the latter have an operculum, while those of the proposed genus have none. 2nd, That the Cypræcassides do not form a complete, thickened lip, before the full period of their growth, like the Cassides. 3rd, That the Cypræcassides have no epidermis. The species mentioned as probably belonging to Cypræcassis are C. rufa, the type; C. coarctata, and C. Testiculus, Auct. The establishment of this genus has been opposed on the ground that indications of epidermis are discoverable in some specimens of C. rufa; that some specimens of the same species and Testiculus have been examined, and found to have formed slightly thickened and dentulated outer lips at very early periods of growth, while many of the other Cassides are destitute of varices, and that an operculum of C. coarctata was brought to this country by Mr. Cuming. It is probable, however, that an increased knowledge of facts might go far to establish the separation. C. Testiculus, fig. 412.

CYPRÆADIA. Sw. A genus of the family "Cypræidæ," Sw. thus described:—"Cypræform; the base contracted; the body whorl not flattened beneath; shell cancellated; aperture of equal breadth throughout; a few thickened, short teeth on the pillar; lip at the base, which is not internally concave. C. cancellata, Sw. Fossil only, differing from Trivea in its contracted base, in the inequality of its aperture, and the equal convexity of the inner lip within." (Sw. Lardn. Cyclop. Malac. p. 325.) Cyprædia, fig. 564.

CYPRÆLA. Sw. A genus formed for the reception of Ovulum verrucosum, Auct. which has a circular depression at each extremity. It is the same as the genus Calpurnus of De Montfort. Ovulum verrucosum, fig. 441.

CYPRÆOVULUM. Gray. A genus of Cypræidæ thus described, "shell like a cowry, but front end of columella covered with regular cross-ribs, like the rest of the base, internally produced into an acute toothed ridge. Shell pear-shaped, cross-ridged." C. capense, fig. 444. South Africa.

CYPRICARDIA. Lam. Fam. Cardiacea, Lam.—Descr. Equivalve, inequilateral, subquadrate, transversely elongated, with the anterior side very short; hinge with three cardinal teeth and one remote lateral tooth in each valve; muscular impressions two in each valve; ligament external.—Obs. This genus is distinguished from Cardita by the three cardinal teeth. The mollusca of this genus are marine. C. angulata, fig. 125. Pacific Ocean.

CYPRINA. Lam. Fam. "Conques Marines," or Marine Conchacea.—Descr. Equivalve, inequilateral, sub-orbicular; umbones curved obliquely; hinge with three diverging cardinal and one remote lateral teeth in each valve; ligament external; muscular impressions two in each valve; palleal impression having a slight posterior sinus; epidermis thick, rough brown.—Obs. The Cyprinæ belong to the Northern hemisphere. The recent species are not numerous. Fossil species are found in the tertiary deposits. Cyprina may be known from Venus by the remote lateral tooth and the thick epidermis. C. vulgaris, fig. 116.

CYRENA. Auct. Fam. Fluviatile Conchaceæ, Lam. Conchacea, Bl—Descr. Suborbicular, equivalve, inequilateral, ventricose, corroded at the umbones, thick, covered with a thick epidermis; hinge with three cardinal and two remote lateral teeth in each valve. Muscular impressions two in each valve; palleal impression not sinuated.—Obs. This genus is distinguished from Venus, Cytherea and Cyprina, by having two remote lateral teeth; and from Cyclas by the thickness of the shell. This genus is mostly fluviatile; the recent species are tropical, and the fossil are found in the newest formations. Fig. 113, C. fuscata.

CYRENELLA. Desh. See Cyrenoides.

CYRENOIDES. Joannis. Cyrenella, Desh. Fam. Conques Fluviatiles, Lam.—Descr. Equivalve, subequilateral, ventricose, thin, covered with a reddish brown epidermis, corroded at the umbones, with a slight posterior fold. Hinge thin, with three diverging cardinal teeth in each valve, and a very slight posterior fold in the right valve. Ligament not very tumid.—Obs. This fresh-water shell differs from Cyclas and Cyrena in the want of lateral teeth, and from the latter in the thinness of the shell. Fig. 114.

CYRTIA. Dalman. (Κυρτος, curtos, gibbose.) Fam. Brachiopoda, Lam.—Descr. "Hinge rectilinear; with the back elevated into a semicone or half-pyramid, the cardinal side perpendicularly plane."—Obs. This genus of fossil Brachiopoda forms part of the genus Spirifer, Sow. C. exporrecta, (Anomites exporrecta, Nonnull.) fig. 204.

CYTHEREA. Lam. Fam. "Conques Marines," Lam.—Descr. Equivalve, inæquilateral, oval, lenticular, or sub-trigonal; hinge with two or more short, diverging cardinal teeth, and one anterior approximate lateral tooth in each valve.—Obs. The Cythereæ are distinguished from the Veneres by the lateral tooth. C. Meretrix, fig. 117, and 117, a. b. c. d.

DACTYLUS. Humph. Marginella, Auct.

DARACIA. Gray. A subgenus of Pyrgoma, including a species which is remarkable for the irregularity of its form. It grows upon a species of Monticularia, and the margin takes the shape of the lobes by which it is surrounded. The aperture is large, and completely closed by the operculum. Daracia (Pyrgoma) Monticulariæ, fig. 489, 490.

DATE. A common name given to shells of the genus Pholas, on account of their cylindrical form and consequent resemblance to the fruit. For the same reason the name Pholas Dactylus has been given by Naturalists to the species which we represent, fig. 66.

DEAD SHELL. A term used among collectors to signify that the shell has been exposed on the sea-shore after the animal has ceased to live. A shell in this condition is worn down by attrition, and loses its beauty and brilliancy of colouring by being subject to the action of salt water. A dead shell may be known by a certain hoary whiteness spread over its surface.

DECACERA. Bl. The second family of the order Cryptodibranchiata, Bl. containing the genera Calmar and Sepia, which have no shells.

DECADOPECTEN. Rüppell. Pecten Plica, Linn. Fig. 172, having a plicated hinge.

DECOLLATED. (Decollari, to be beheaded.) The apex or nucleus of some shells being composed of a more fragile substance than the rest, has a tendency to fall off. The reason of this probably is that the animal withdrawing from that part, leaves it unprotected. When it falls off, the hole is stopped up by a septum filling the cavity of the volution, so as to exclude the air: the shell is then said to be decollated. Ex. Bulinus decollatus, fig. 289.

DECUSSATED. Intersected by striæ crossing each other. Ex. Rissoa, fig. 346.

DELPHINULA. Montf. (Delphinus, a dolphin.) Fam. Scalariens, Lam. Cricostomata, Bl.—Descr. Orbicular, depressed, thick, rugose; whorls few, angulated, branched at the angles; aperture pearly, rounded or sub-quadrate; peritreme continuous, thickened; operculum horny, composed of numerous whorls.—Obs. Several fossil species are found in the tertiary deposits. D. laciniata, fig. 352. Recent species belong to tropical climates.

DELTHYRIS. Dalman. Fam. Brachiopoda, Lam.—Descr. Hinge more or less rounded, with distant umbones; both valves convex; with the umbo of the largest rostrated and deltoid, with a hollow. This genus forms part of the genus Spirifer, Sow. Fig. 205. D. Plycotes, Dalman.

DELTOID. (Δ, delta.) Triangular.

DENDOSTREA. Sw. (Δενδρον, dendron, tree; οστρεον, ostreon, oyster.) Ostrea Crista-galli, and other species which are attached to stems of sea-weed and corallines, by means of arms thrown out from the inner surface of the lower valve. Fig. 181, Ostrea Folium.

DENTALIUM. Auct. (Dens, a tooth.) Fam. Maldania, Lam. Order, Cirrobranchiata, Bl.—Descr. Tubular, arched, increasing in size towards the anterior extremity, open at both ends; small aperture sometimes having a lateral fissure; large aperture round; external surface ribbed, striated or smooth.—Obs. The well known shells composing this genus are shaped very much like an elephant's tusk, and are not liable to be confounded with any other genus. The fossil species are sometimes termed Dentalithes, from dens, a tooth, and lithos, a stone. The Dentalia, being true molluscs, are not rightly placed among the Annelides. Fig. 2, D. octogonum. Found on sandy shores in most climates.

DENTATED. Having teeth or raised points.

DENTICULATED. (Denticulatus, Lat.) Having little teeth or raised points.

DEPRESSED. Flattened, pressed down, as the spires of some shells.

DEXTRAL Spiral Shells. Place the point of a spiral shell towards the eye, with its mouth downwards; if, as in most instances, the aperture be on the right side of the axis, it is a dextral shell, if otherwise, it is sinistral or reversed. Balea (fig. 296), and Clausilia (fig. 295), are examples of reversed shells.

DEXTRAL Valve. Take a bivalve shell closed, place it before the eye, with the umbones uppermost, and the posterior side, which may be known by the ligament towards the observer, whose right side will then correspond with the right valve of the shell.

DIADEMA. Ranz. Coronula Diadema, Auct. fig. 17.

DIANCHORA. Sow. Fam. Pectinides, Lam. Order, Palliobranchiata, Bl.—Descr. Inequivalve, attached, oblique, subtriangular; attached valve, having an opening in the place of the umbo; the other valve auriculated, with an obtuse umbo; hinge without teeth.—Obs. The green sand fossils contained in this genus differ from Plagiostoma in being attached. Fig. 175, D. striata.

DIAPHANOUS. (Δια, dia, through; φαινω, phaino, to shine.) Transparent.

DIAPHRAGM, (διαφραγμα, a partition.) This term is applied to the septa, by which the chambers of multilocular and other shells are divided from each other.

DICERAS. Lam. (Δις, dis, double; Κερας, ceras, horn.) Fam. Chamacea, Bl. and Lam.—Descr. Inequilateral, inequivalve, attached by the point of the umbo of the larger valve; umbones prominent, spirally twisted and grooved; hinge with one large thick tooth in the larger valve; muscular impressions, two in each valve.—Obs. The prominent spiral umbones, which give rise to the name of this genus, with the circumstance of its being attached by the point of one of them, is sufficient to distinguish it from any other, although it appears to approach Isocardia in some characters. In others it will be found still more nearly to resemble Chama. In fact, from being attached and irregular, the shells composing this genus have been considered as Chamæ with produced umbones. The singular fossil shells composing this genus, are found in granular limestone, near Geneva and in Normandy. Fig. 154, D. perversum.

DIDONTA. Schum. Saxicava. Auct.

DIFFUSE. (Diffundo, to spread out, to dilate.) A term applied to the aperture of a univalve shell, when it is spread out or widened into a flat surface, or digitations. Alated is another term used to express the same character. Thus, the shells belonging to the family of Alatæ, in the system of Lamarck, are diffuse in the outer lip. Fig. 402 to 406.

DIGITATED. (Digitus, finger.) Branched out in long points, as Ricinula, fig. 413.

DILATED. Expanded, spread. This term has the same application as diffuse and alated, explained above. The outer lip of Rostellaria Columbaria, fig. 403 (Hippochrenes, Montf.), will serve as an example.

DIMORPHINA. D'Orb. A genus of microscopic Foraminifera.

DIMYARIA. (Δις, dis, double; μυον, myon, muscle.) The first order of Conchifera, Lam. including those molluscs which have two adductor muscles, and consequently two muscular impressions in each valve. The Conchifera Dimyaria are divided into Crassipedes, Tenuipedes, Lamellipedes, and Ambiguæ, fig. 44 to 155.

DIOICA. Bl. The first division of the class Paracephalophora, Bl. It is divided into the orders Siphonobranchiata and Asiphonibranchiata, Bl.

DIPLODON. Spix. Hyria Syrmatophora, Lam. fig. 144, and Unio multistriatus, Lea, are doubtfully quoted by Lea as belonging to this apparently ill-defined genus of Nayades.

DIPSAS. Leach. A genus or sub-genus of Nayades, the distinctive character of which is "having a linear tooth under the dorsal edge." D. plicatus, fig. 142.

DISCINA. Lam. Orbicula, Auct.

DISCODOMA. Sw. A sub-genus of Lucerninæ, Sw. (Helix), thus described, "teeth none; aperture angulated; the inner lip nearly obsolete; the outer only slightly thickened; margin carinated."

DISCOIDAL. (Discus, a circular plane.) A spiral shell is said to be discoidal, when the whorls are so horizontally convolute as to form a flattened spire. Ex. Planorbis, fig. 311. Orbulites Discus, fig. 479.

DISCOLITES. Montf. A genus of microscopic Foraminifera.

DISCONTINUOUS. Interrupted. Ex. The siphon of Nautilus is discontinuous, i. e. its termination in one chamber does not reach to its commencement in the next. The varices of Triton, occurring in different parts of the whorls, do not form the continuous ridges which characterize the generality of the Ranellæ.

DISCORBITES. Lam. A genus of microscopic Foraminifera.

DISTANT. The teeth on the hinge of a bivalve shell are said to be distant when they are remote from the umbones.

DIVARICATED. Diverging, meeting in a point, as the teeth on the hinge of Placuna, fig. 184.

DOLABELLA. Lam. (Dim. from Dolabra, a hatchet.) Fam. Aplysiacea, Lam. and Bl.—Descr. Hatchet-shaped, arched, covered with a horny epidermis; posteriorly attenuated, thickened, sub-spiral, anteriorly plane, broad, thin; posterior margin reflected.—Obs. The two or three species of Dolabella known are inhabitants of the Indian Ocean. They were placed by Linnæus in his very convenient genus Bulla, under the name B. dubia. Fig. 255, Dolabella Rumphii.

DOLIUM. D'Argenville. (a tun.) Fam. Purpurifera, Lam. Entomostomata, Bl.—Descr. Thin, ventricose, oval, or globular, with a short spire; large aperture terminating in a reflected canal, and spirally ribbed or grooved external surface; outer lip crenated; inner lip reflected over part of the body whorl, which terminates in a tumid varix; epidermis light, horny. Mediterranean and East Indian.—Obs. This genus is distinguished from Cassis by the outer lip, which is not reflected. The species which are not so rotund as the others, as D. Perdix, Auct. have been separated under the name Perdix, as generic. Fig. 420, Dolium Maculatum.

DONAX. Auct. Fam. Nymphacea, Lam. Conchacea, Bl.—Descr. Equivalve, inequilateral, trigonal, with the anterior side short, straight, plane; the posterior side elongated, drawn to a narrow, rounded termination; hinge with two cardinal teeth in one valve, one in the other, and one or two, more or less remote lateral teeth; ligament external; muscular impressions two in each valve; palleal impression sinuated posteriorly.—Obs. The Capsæ have not the crenated margins, the short anterior side, and the distinct lateral teeth, which characterize the Donaces. Some species of Erycina resemble Donax in general form, but are at once distinguished by the ligamentary pit in the hinge. Sandy shores in all climates. Fig. 108, D. cuneatus.

DORSAL. A dorsal shell is one placed upon the back of the animal. The dorsal margin of a bivalve shell is that on which the hinge is placed; the opposite margins are termed ventral. The dorsal surface of a spiral univalve is that which is seen when the aperture is turned from the observer. The dorsal valve is the uppermost in Brachiopodous bivalves. The dorsal part of a symmetrical convolute univalve, such as the Nautilus and Ammonite is that part of the whorls which is at the greatest distance from the spire, that is, the outer part of the whorls. Thus the situation of the siphon is said to be dorsal when it pierces the septum near the outer edge of the whorls. The dorsal part of symmetrical conical univalves, such as Patella, is the upper part, on which the apex is placed.

DORSALIA. Lam. (Dorsum, the back.) The first family of the order Annelides Sedentaria, Lam. containing the genera Arenicola, not a shell, and Siliquaria, fig. 1, which is now considered as a true mollusc, and placed next to Vermetus.

DOSINA. Schum. Venus Verrucosa, Casina, and similar species. Fig. 119, a.

DREISSINA. Mytilus Polymorphus. Auct. fig. 159. This genus differs from Mytilus principally in the characters of the animal. The shell is characterized by a small septiform plate under the hinge within. Fluviatile, Europe and Africa.

EBURNA. Lam. (Eburneus, ivory.) Fam. Purpurifera, Lam. Entomostomata, Bl.—Descr. Oval, thick, smooth, turrited, umbilicated; spire angulated, acute, nearly as long as the aperture; aperture oval, terminating anteriorly in a canal, posteriorly in a groove; outer lip slightly thickened with an anterior notch, which terminates in a spiral fold surrounding the body whorl; umbilicus generally covered by the thickened columellar lip.—Obs. The beautiful shells called ivory shells, which originally constituted part of this genus, are now placed in the genus Ancillaria by authors. They differ from the present genus Eburna, in having the sutures of the spire covered with a polished enamel. (A. glabrata, fig. 455.) The Eburnæ resemble in some respects the genus Buccinum, but a glance at the figure will enable the reader to distinguish a true Eburna from all other shells. Fig. 426 is Eburna Zeylanica. A catalogue of 9 species is given in part 20 of the Conchological Illustrations published by the Author, accompanied by figures of several species.

ECHIDNIS. Montf. Described as a straight, chambered, annulated, fossil shell, computed from the extremely gradual increase in diameter of the fragments to be at least sixteen feet long. Found in marble from the Pyrenees.

ECHINELLA. Sw. A sub-genus of Monodonta. Sw. Malac. page 352.

EFFUSE. (effundo, to pour out.) The aperture of an univalve shell is said to be effuse when there is a notch in the margin which would suffer a liquid to escape, and thus prevent it being filled to the brim.

EGEON. Montf. A genus of microscopic Foraminifera.

EGERIA. Lea. (Contrib. to Geol. p. 49, pl. 1.) A genus of fossil bivalves, described as very variable in form, with or without lateral teeth, sometimes a crenated margin, &c. The only certain characters appear to be that they have two diverging cardinal teeth in each valve, one of which is bifid; and an external ligament. Lea states that the Egeriæ should be placed between the Sanguinolariæ and the Psammobiæ, which two latter genera have been united by Sowerby. Fig. 103, E. Triangulata, from the tertiary formation of Alabama.

ELENCHUS. Humph. A genus composed of Trochus Iris, Auct. and other similarly formed species. It is the same as Cantharidus of Montfort.

ELEPHANT'S TUSK. The common name given by dealers to shells of the genus Dentalium. Ex. D. octogonum, fig. 2.

ELEVATED. A term which is applied by some conchological writers to the spire of an univalve shell when it consists of numerous whorls drawn out into a telescopic form. Other authors use the term elongated, or the more simple one 'long,' to express the degree of elevation.

ELISMA. Leach. A sub-genus of Bulinus. B. acutus, Auct. Gray, Turton, p. 185.

ELLIPSOLITHES. Montf. (Ελλειψις, ellipsis, oval; λιθος, lithos, stone.) A genus composed of Ammonites, which instead of being regularly orbicular, take an elliptical or oval form. This character appears to be accidental, as some individuals of the same species, both of Nautilus and Ammonites, are round, while others are compressed into an oval form.

ELLIPSOSTOMATA. Bl. (Ελλειψις, ellipsis, oval; στωμα, mouth.) The third family of the class Asiphonibranchiata, Bl. The shells of this family are described as of various forms, generally smooth; the aperture longitudinally or transversely oval, completely closed by a horny or shelly operculum. This family contains the genera Rissoa, Phasianella, Ampullaria, Helicina, and Pleuroceras.

ELLIPTICAL. (Ελλειψις, ellipsis.) Oval. Applied to any shell or part of a shell, having that form.

ELMINEUS. Leach. Order, Sessile Cirripedes, Lam.—Descr. Four unequal valves, arranged circularly side by side, forming a quadrate cone; aperture large, sub-quadrate, irregular; operculum composed of four valves, in pairs.—Obs. This genus differs from Conia in the structure of the shell, the latter being porous. Fig. 22, Elmineus Leachii.

ELPHIDIUM. Montf. (Conch. Syst. t. 1. p. 15.) A genus of microscopic Foraminifera.

EMARGINATED. (e, out; margo, border.) Notched or hollowed out. Applied to the edges or margins of shells, when instead of being level they are hollowed out, as the outer lip of Oliva, fig. 457, at the base, and the ventral margins of some bivalves.

EMARGINULA. Lam. (e, out; margo, border.) Fam. Calyptracea, Lam. Branchifera, Bl.—Descr. Patelliform, oblong or oval; anterior margin notched or emarginated; apex posteriorly inclined; muscular impressions wide.—Obs. Emarginula elongata, of some Authors, Parmophorus of De Blainville is commonly called the Duck's bill limpet, from its shape. The Emarginulæ may be known from Patellæ and other neighbouring genera, by the notch or slit in the anterior edge. In the genus Rimula, Defr. fig. 243, this slit is near the apex, and does not reach the margin. Recent species occur in all climates, but are not numerous. Fossil species are still more rare, occurring in the Calc-grossièr, Crag and Oolite. E. fissurata, fig. 241.

ENA. Leach. A sub-genus of Bulinus. B. Lackhamensis. Mont.

ENDOSIPHONITES. A genus composed of Ammonites, having the siphon close to the body whorl, fig. 476.

ENDOTOMA. Rafinesque. A genus of microscopic Foraminifera.

ENROULEES. Lam. See Convolutæ.

ENSATELLA. Sw. A genus consisting of Solen ensis, Auct. fig. 60, and other species similarly curved. Genus Ensis, Schum.

ENSIS. Schum. Solen ensis, Auct. and similar species.

ENTALIS. Defr. Dentalium duplicatum, Bl. Pharetrium, König. This genus is described as a small tube, within a larger one, the smaller extremity of the inner tube projecting beyond that of the outer one. Deshayes, who describes this genus, expresses a conviction that the soft parts of the animal must be entirely different from those of the animal of Dentalium. The genus Pharetrium, as described by König in his "Icones Fossilium Sectiles," is evidently identical with Entalis. It is placed by him in the family of Pteropoda, but being a fossil shell, there is some difficulty in finding its place in the system. See plates, fig. 3.

ENTELLITES. Fischer. A genus composed of species of Terebratula, Spirifer, and Productus, Auct. having the hinge large and the umbones short. Orthis? Dalman.

ENTIRE. (Integra.) Not interrupted, not emarginated. The peritrême of a univalve shell is said to be entire when not interrupted by canals or by the body whorl. Ex. Cyclostoma, fig. 304. The palleal impression is entire, when continued without interruption, or without a sinus.

ENTOMOSTOMATA. Bl. The second family of the order Siphonibranchiata, Bl. The shells of this family are described as differing but little from those contained in the family of Siphonostomata of the same author, both with regard to the soft parts, and their testaceous covering. This family partly answers to the Purpuriferæ in the system of Lamarck, and contains the genera Subula, Cerithium, Melanopsis, Planaxis, Terebra, Eburna, Buccinum, Harpa, Dolium, Cassidaria, Cassis, Ricinula, Cancellaria, Purpura, Concholepas.

EOLIDES. Montf. A genus of microscopic Foraminifera.

EPIDERMIS. (Επι, epi, over or upon; δερμα, derma, skin.) The fibrous, horny, external coating of shells, called by the French, "Drap marin," or marine cloth. Lamarck objects to the name Epidermis because he does not consider the substance as answering to the cuticle or scarf skin of the human body, but more analogous to the nails and hair. Gray calls it the Periostracum, from the membranous skin covering the bones of quadrupeds.

EPIPHRAGM. The membranaceous or calcareous substance by which some species of molluscs close the aperture of the shell, when they retire within it to hibernate. When the animal wishes to come forth from his hiding-place, again to breathe the air, the edges of the Epiphragm are detached by a chemical process, so that it drops off. The name Hibernaculum has also been given to this covering. It must not be confounded with the operculum, which is a permanent portion of the shell, and is used as a door, fitted to the foot of the animal and moved at will to open or close the aperture of the shell, whereas the Epiphragm is produced for the occasion from a mucous secretion of the animal and dissolved at the edges when no longer wanted, when it drops off.

EPISTYLA. Sw. A subgenus of the genus Helix. E. conical. Sw. Helix Epistylium, fig. 281.

EPONIDES. Montf. A genus of microscopic Foraminifera.

EQUILATERAL. (Æquus, equal; latus, side.) Equal-sided. A term applied to bivalve shells, when a line drawn down perpendicularly from the apex would divide the shell into two equal parts. Ex. Pectunculus pilosus, fig. 134.

EQUIVALVE. (Æquus, equal; valva, a valve.) A term applied to a bivalve shell when the valves are equal to each other in dimensions.

ERATO. Risso. Fam. Convolutæ, Lam.—Descr. Ovate, more or less angulated, smooth or granulated, with a dorsal scar; spire short; aperture large, angulated, emarginated; columella slightly crenated; outer lip reflected, denticulated on the inner edge. Suture of the whorls covered with enamel.—Obs. This genus of shells resembles Marginella in form, but has no folds on the columella. Having a scar or groove down the back it may be considered intermediate between Marginella and Cypræa. Fig. 454, E. Maugeriæ. In the Author's Conchological Illustrations, seven species are enumerated and figured.

ERUCA. Sw. A subgenus of Clausilia. Sw. Malac. p. 334.

ERVILIA. Turt. A genus described as "oval, equivalve, equilateral, closed. Hinge with a single erect tooth closing between two small diverging ones in the opposite valve: lateral teeth none. Ligament internal. E. nitens. Turt. Mya. nitens, Auct."

ERYCINA. Lam. Fam. Mactracea, Lam. Conchacea, Bl.—Descr. Ovate or triangular, transverse, equivalve, inequilateral, smooth; hinge with a ligamentary pit, two diverging cardinal and two lateral teeth in each valve; muscular impressions two in each valve; palleal impressions sinuated. East and West Indies and Mediterranean.—Obs. This genus is distinguished from Mactra and Lutraria by the cardinal teeth being placed one on each side of the ligamentiferous pit; whereas in the last named genera they are both placed on the anterior side. Fig. 86, E. Plebeja.

ERYTHRÆA. The ancient name for Cypræa.

ESCUTCHEON. The impression on the posterior dorsal margin of some bivalve shells. That on the anterior margin is named the lunule. The escutcheon is pointed out by the letter e in some of the figures of Cythereæ. Fig. 117, a. b. c.

ETHERIA. Lam. (Æther, air.) Fam. Chamacea, Lam. and Bl.—Descr. Irregular, inequivalve, inequilateral, foliaceous, pearly within, covered by an olive green epidermis without; hinge callous, undulated, destitute of teeth; ligament partly external, partly internal, passing through the hinge on a somewhat raised, callous area in the lower valve. Muscular impressions elongated, two in each valve, united by a slender palleal impression. Rivers of Africa.—Obs. The irregular, unequal air-bubbles of the inner surface, whence this genus derives its name, are very brilliant in some species, and atone, in some measure, for the rugged ugliness of the exterior. In its irregular form, foliated structure, and toothless hinge, it resembles Ostrea, from which it differs in having two muscular impressions. Fig. 155, E. semilunata.

EULIMA. Risso. Fam. Scalariens, Lam.—Descr. Elongated, smooth, pyramidal; spire long, composed of numerous whorls; apex acute, slightly tortuous; aperture oval, rounded anteriorly, acute at the posterior union with the body whorl; outer lip slightly thickened; columella smooth. Fig. 347, E. labiosa, fig. 348, E. splendidula. A complete illustrated monograph of this genus of pretty shining little shells, consisting of 15 known species, is given in parts 52 and 53 of the Conchological Illustrations by the author.

EUOMPHALUS. Sow. Fam. Scalariens, Lam.—Descr. Orbicular, planorbular spire, with three or four volutions, imbricated above; smooth below; aperture of a round polygonal form; umbilicus large, penetrating to the apex of the shell.—Obs. This genus of fossils very nearly resembles Delphinula. The main difference appears to be that the whorls do not increase so rapidly in size in the former as in the latter. Fossil, in the Carboniferous Limestone. Fig. 350.

EXOGYRA. Sow. A genus of fossil bivalves, resembling Chama in shape and Ostræa in structure, having but one muscular impression in each valve. Fig. 183.

EXSERTED. Standing out, protruding.

EXTERNAL. An external shell is one which contains the animal, and is not covered by the mantle.

FASCIATED. (fascia, a band.) Banded or striped. Ex. Carocolla marginata, fig. 277.

FASCICULATED. (from fasciculum.) A little bunch of hairs or bristles against each end of each valve, characterizes some species of the genus Chiton, which are termed fasciculated species.

FASCIOLARIA. Lam. Fam. Canalifera, Lam. Siphonostomata, Bl.—Descr. Elongated, fusiform, ventricose; spire conical, consisting of few rounded or angulated whorls; aperture wide, terminating in a long straight open canal: columella lip with several oblique folds, the lower of which is larger than the rest; operculum horny, pyriform.—Obs. This genus is known from Fusus by the folds on the columella; from Turbinella, by their obliquity and the last being larger than the rest. Fig. 386, F. Trapezium. East and West Indies and Australia.

FAUNUS. Montf. Melanopsis, Auct.

FERRUGINEOUS. Of an iron rust colour.

FERUSSINA. Grateloup. Strophostoma, Deshayes.

FIBROUS. A shell is said to be of a fibrous structure when a fracture would present a series of perpendicular fibres, as Pinna.

FICULA. Sw. A generic group of shells, consisting of those species of Pyrula, Auct. which have the true pear-shaped character. Fig. 390, P. Ficus. Sowerby confines the name Pyrula to these species.

FIMBRIA. Megerle. Corbis, Lam.

FIMBRIATED. Fringed; as Murex fimbriatus, a delicate white species, with broad fringed varices.

FISSURE. (Fissura, a slit.) A slit or cut, a narrow perforation, as in Emarginula and Fissurella.

FISSURELLA. Brug. (Fissura, a fissure.) Fam. Calyptracia, Lam. Branchifera, Bl.—Descr. Patelliform, oval or oblong, radiated; apex anterior, perforated.—Obs. The Fissurellæ are known from Patellæ by the perforation in the apex. Fig. 245. The catalogue published by the author in the Conchological Illustrations, enumerates 68 species.

FISTULANA. Lam. (Fistula, a pipe.) Fam. Tubicolæ, Lam. Adesmacea, Bl.—Descr. A transversely elongated, equivalve, inequilateral bivalve, enclosed by a septum within the widest, closed extremity of a straight calcareous tube. Fistulana is known from Gastrochæna by the straightness of the tubes, and the oblong state of the valves. Fig. 54, Fistulana Clava.

FLEXUOUS. Having windings or bendings. Ex. The Tellinæ are known by the twist or flexuosity in the posterior ventral margin of the shell.

FLORILLUS. Montf. A genus of microscopic Foraminifera.

FLUVIATILE. (Fluviatilis.) Belonging to a river or running stream. Ex. Limnæa fluviatilis.

FLUVIATILE CONCHACEA. See Conchacea.

FOLIATED, or FOLIACEOUS. (From folium, a leaf.) When the edges of the successive layers of which a shell is composed are not compacted but placed apart from each other, projecting like tiles, the shell is said to be of a foliated structure. The common Oyster, fig. 180, presents a familiar example.

FORAMINIFERA. D'Orb. (Foramen, a hole or pit.) An order established for minute many chambered internal shells, which have no open chamber beyond the last partition. Lamarck, D'Orbigny, and other writers have placed them among the Cephalopoda in their systems, but Du Jardin, on comparing the fossils with some recent species of the same class, arrived at the conclusion, now generally adopted, that they constitute a distinct class, much lower in degree of organization than even the Radiata. Not recognizing these microscopic bodies as shells, properly so called, but considering them sufficiently numerous and interesting to form a distinct branch of study, I do not think it desirable to describe the genera, or to present any arrangement of them in this work.

FORNICATED. Arched or vaulted, as the exfoliations on the costæ of Tridacna Elongata, fig. 157.

FOSSIL SHELL. A shell is considered to be in a fossil state when, the soft parts having ceased to exist, it is deprived of all its animal juices, has lost all, or nearly all its natural colour, and is thus changed in its chemical composition, when little or nothing is left but a mere bone, which is embedded in a sedimentary deposit. In this state, it is fragile, prehensile to the tongue, and either destitute of colour or tinged with the diluted mineral matters which pervade the stratum in which it lies. In some cases, the mineral composition of the shell is so completely changed as no longer to present its proper structure, consisting of successive oblique layers of shelly matter; but is altered into a fibrous structure, composed of rhomboidal particles. An example of this will be found in the Belemnites, which if broken, shew the perpendicular fibres. In other cases, the matter which has entered and filled up the cavities of the shell has become silicified, or changed into flint, and the shell itself has been decomposed and fallen off, so as to leave nothing but an external or internal cast of its form, in flint. This is called a Conchyliomorphite by continental writers. Some of the most important of Geological data are obtained by a minute comparison of fossil shells, found in various beds, with recent ones presenting the nearest resemblance to them. Some species of fossil shells are considered as identical with recent species. And many Geologists seek to fix the chronology of the different strata by the number of species which they inclose bearing a resemblance to the recent species. Indeed, all who would study Geology with success, will find it indispensably necessary to obtain a thorough knowledge of Conchology.

FRAGELLA. Sw. A sub-genus of Monodonta, corresponding with the genus Clanculus, Montf. consisting of M. Pharaonis (fig. 361), and similar species. Sw. p. 352.

FRAGILE. (Fragilis.) Tender, easily broken.

FREE SHELL. One that is not attached.

FREE VALVE. In attached bivalve shells, one only is fixed; the other is then free, as far as to the action of opening and shutting.

FRESH-WATER SHELLS, (sometimes described as aquatic) are those which either inhabit rivers, running pools and ditches, in which case they are fluviatile; or wells and ponds of standing water, &c. Fresh-water shells are either thin and horny in their texture, as the Limneana of Lamarck; or are covered with a compact, smooth, horny epidermis. They are generally simple in form, subject to corrosion where the epidermis is wounded or broken, and are circumscribed with regard to the classes and genera to which they belong. The family of Nayades includes nearly all the fresh-water bivalves; and the Melaniana and Limneana are the principal among univalves.

FRONDICULARIA. Defr. A genus of microscopic Foraminifera.

FRONT. The surface of a shell on which the aperture appears.

FULCRUM. That part of a shell on which any other part rests or turns. The term is applied more particularly to the tumid part in the hinge of bivalve shells on which the ligament is fixed.

FULGUR. Montf. Pyrula perversa, Auct. and such other species as have an angulated spire. Fig. 388.

FUSIFORM. (Fusus, a spindle.) Shaped like a spindle, swelling in the centre and tapering at the extremities. Ex. Fusus, fig. 387.

FUSUS. Brug. (A spindle.) Fam. Canalifera, Lam. Siphonostomata, Bl.—Descr. Fusiform, turrited, with many rounded whorls; aperture generally oval, terminating in a long straight canal; operculum horny, pyriform.—Obs. The Fusi are subject to considerable variations in form. The recent species are numerous and do not appear to be confined to any climate. The fossil species are also numerous, chiefly abounding in the tertiary formations. The recent species are mostly tropical. Fig. 387, F. Colus.

GALATHÆA. Brug. Potamophila, Sow. Megadesma, Bowd.

GALEA. Klein. Purpura, Auct.

GALEOLARIA. Lam. (From Galea, a helmet or crest.) A genus composed of species of Serpula, Auct. Distinguished as being fixed by the side of the shell, and having the anterior extremity erect, the aperture terminating in a tongue-shaped projection.—Obs. This genus is said by Lamarck to resemble Vermilia in other respects, but to differ in having the anterior part raised. Fig. 6, G. decumbens. Africa and Australia.

GALEOMMA. Turt. Fam. Pholadaria, Lam.—Descr. Thin, oval, equivalve, equilateral, with the ventral margin gaping; hinge with one cardinal tooth in each valve; muscular impressions two, approximate; palleal impression interrupted, not sinuated; ligament small, partly internal, partly external, fixed on a prominent fulcrum.—Obs. The wide hiatus in the ventral margins of this equilateral shell prevents the possibility of confounding it with any other. Four or five recent species are known, one of which is found on the coast of Sicily, and also in the British Channel. G. Turtoni, fig. 58.

GALERICULUS. (Galericulum, a little cap or bonnet.) Velutina, Auct. fig. 337.

GALERUS. Humph. Calyptræa, Lam.

GAPING. (Hians.) Bivalve shells are said to gape when the margins do not meet all round. Ex. Gastrochæna, fig. 52.

GARI. Schum. Psammobia, Lam.

GASTEROPODA. Lam. (Γαστηρ, gaster, belly; πους, ποδος, pus, podos, a foot.) The second order of the class Mollusca, Lam. containing those molluscous animals whose organs of locomotion are ventral. Most of the shells belonging to this order are patelliform, placed upon the back of the animals, which rest or crawl upon the belly. This order is divided into Pneumonobranchiata, that is, those which breath air, or land molluscs; and Hydrobranchiata, or those which breath water, marine or fresh-water molluscs. Fig. 227 to 263.

GASTRANEA. Schum.? Corbula, Auct.

GASTROCHÆNA. Speng. (Γαστηρ, gaster, belly; χαινο, chaino, gape.) Fam. Pholadaria, Lam. Pyloridea, Bl.—Descr. Equivalve, regular, inequilateral, with a wide, oblique, ventral hiatus, enclosed in a curved pyriform tube. Differing from Galeomma in being a free, oblique shell; from Fistulana, in the oval shape of the valves, and the curve of the tube; from Aspergillum and Clavagella, in both valves being free.—Obs. The Gastrochænæ are found in the hollows of massive shells or other marine substances. Fig. 62, G. Modiolina.

GASTROPLAX. Bl. Umbrella, Lam. De Blainville described this genus from a specimen in which the shell had been, probably by accident, placed upon the under part of the animal, and not discovering his error until afterwards, gave it the above name.

GEOMITRA. Sw. A sub-genus of Geotrochus, Sw. founded on a trochiform species of Helix, with coronated nodules on the whorls. Helix bicarinata, Sow. Zool. Journ. 1, pl. 3, fig. 7. Sw. page 166 and 332.

GEOPHONUS. Montf. Conch. Syst. t. 1, p. 19. A genus of microscopic Foraminifera.

GEOTROCHUS. Sw. Helix pileus, Auct. (fig. 278,) and other trochiform species. Divided into the sub-genera Pithohelix, Geotrochus, Hemitrochus, Gonidormus, and Geomitra. Sw. p. 165 and 166, described at page 331.

GEOVULA. Sw. A sub-genus of Melampus (Auricula), consisting of oval species, resembling Auricula Midæ, fig. 297.

GERVILLIA. Defr. Fam. Margaritacea, Bl. Malleacea, Lam.—Descr. Equivalve, oblong, oblique; hinge long, straight, having small, irregular, transverse ligamentary pits.—Obs. This genus of fossil shells, found at various geological periods, from the Lias to the Baculite limestone in Normandy, is now extinct. In general form it resembles Avicula, but in the hinge it approaches Perna. Fig. 169, G. Avicularis.

GIBERULA. Sw. A genus separated from Marginella, Auct. and thus described, "sub-oval; spire slightly prominent; top of the outer lip dilated and gibbous; base of the inner lip with plaits; inner lip broad, spreading. G. Zonata. Enc. Méth. 374, f. 6."

GIBBOSE or GIBBOUS. (Gibbosus.) Bunched out, embossed, having a lump or swelling of any kind. Ex. Bulinus Lyonetianus, (fig. 284.) named Gibbus by De Montfort. Ovulum gibbosum.

GIBBUS. Montf. Bulinus Lyonetianus, Lam. Pupa, Bl. fig. 284.

GIOENIA. A name given in the Encyclopédie Méthodique, to the plates of the stomach of Bulla Lignaria.

GLABELLA. Sw. Marginella Glabella (fig. 437), Goodallii, Auct. and similar species.

GLANDINA. Schum. Polyphemus, Montf.

GLANDIOLUS. Montf. A genus of microscopic Foraminifera.

GLAUCONOME. Gray. Fam. Solenacea, Lam.—Descr. Oblong or oval, transverse, slightly ventricose, equivalve, inequilateral; margins close, rounded anteriorly, somewhat acuminated posteriorly; hinge teeth, three in each valve, of which the central in one, and the posterior in the other, are bifid; muscular impressions anterior, elongated, marginal; posterior sub-quadrate; palleal impression, having a long sinus; ligament oblong, external; epidermis thin, horny, green, folded over the margins.—Obs. This shell, of which only one species is known, inhabits some of the rivers in China. C. Chinensis, fig. 64.

GLOBIGENERA. D'Orb. A genus of microscopic Foraminifera.

GLOBOSE. (Globosus.) Rounded like a globe or ball, as the species of Helix, represented in fig. 268.

GLOBULARIA. Sw. A sub-genus of Natica, consisting of globose species. (Sw. p. 345.) Ex. N. Lineata, fig. 328.

GLOBULUS. Sow. Min. Con. Ampullaria, Auct.

GLYCIMERIS. Lam. Fam. Solenacea, Lam. Pyloridea, Bl.—Descr. Equivalve, transverse, oblong, thick, compressed, gaping at both extremities; hinge callous, without teeth; ligament large, external, prominent; epidermis thick, black, horny, folded over the margins; muscular impressions two, distant, running into the irregular palleal impression which unites them.—Obs. But few species of this singular genus are known; Lamarck describes two species from the Northern Seas. Blainville is of opinion that they belong to the family of the Nayades. Fig. 67, G. Siliqua.

GNATHODON. Gray. (Γναθος, gnathos, jaw-bone; οδος, οδοντος, odontos, tooth.) Fam. Mactracea, Lam.—Descr. Ovate, posteriorly angulated, equivalve, thick, ventricose, inequilateral, covered with a greenish brown epidermis; umbo distant, prominent; hinge having in one valve a sharp, angular, notched, cardinal tooth, and two lateral teeth, the posterior of which is elongated, and the anterior angulated, tortuous, shaped like a jaw-bone; in the other valve, two cardinal and two lateral teeth, the anterior of which is wedge-shaped; ligament internal, cuneiform, placed in a deep cardinal pit proceeding from the umbones; muscular impressions two; palleal impression having a slight sinus.—Obs. Only one species is known, G. cuneatus, fig. 83, from New Orleans. It is known from all other shells by the character of the hinge.

GONIATITES. De Haan. A genus composed of species of Ammonites, Auct. in which the last whorl covers the spire and the sinuations of the septa are angulated. Fig. 480, G. striatus.

GONIDOMUS. Sw. A sub-genus of Geotrochus, Sw. Pupa pagodus, Auct. Sw. p. 332.

GONIOSTOMA. Sw. A sub-genus of Bulimus, thus described, "spire elongated, of few whorls; aperture contracted at each end; lips margined; the pillar curving inwards; the base slightly notched. G. erubescens, Sw. Zool. Journ. i. pl. 5, f. 2." Sw. p. 335.

GONIOSTOMATÆ. Bl. A family belonging to the order Asiphonibranchiata, Bl. containing the genera Solarium and Trochus.

GONOSPIRA. Sw. A sub-genus of Pupa, thus described, "spire perfectly cylindrical, of equal thickness, the tip obtuse, with the whorls large; aperture oval; lips thickened; pillar with or without a plait. G. polanga, Desh. Lesson, Voy. pl. 8, f. 8." Sw. p. 333.

GRANULATED. (Granum, a grain.) Covered with minute grains, rough. The granulated lip of Oniscia, (fig. 409) will serve as an example.

GRATELOUPIA. Moulins. Fam. Nymphacea, Lam.—Descr. Equivalve, inequilateral, sub-cuneiform, rounded anteriorly, sub-rostrated posteriorly; hinge with three cardinal teeth, a series of five or six irregular, small, diverging teeth behind the umbones, and one lateral anterior tooth in each valve; ligament external; muscular impressions two; palleal impression sinuated posteriorly.—Obs. This genus (Donax irregularis, Bast.) is only known in a fossil state. Fig. 102, G. Moulinsii.

GRYPHÆA. Lam. (From Gryps, a griffin.) Fam. Ostracea, Lam.—Descr. Inequivalve, free; lower valve large, concave; with the umbo prominent, incurved; upper valve small, flat, opercular; hinge toothless, with a curved, depressed area; one muscular impression.—Obs. These shells, which approach the Oysters, are of a more regular form, and are remarkable for the curved, produced beak of the lower valve. They are only known in a fossil state, belonging to the more ancient strata. Fig. 182, G. incurva. The recent species mentioned by Lamarck is not a true Gryphæa.

GYMNOLEPAS. A generic name used by De Blainville to include Otion and Cineras, Leach.

GYMNOSOMATA. Bl. The second family of the order Aporobranchiata, in the system of De Blainville. The animals belonging to this family are destitute of shells.

GYPIDEA. Dalman. A genus of Brachiopoda, thus described, "Larger valve with the umbo rostrated, remote from the hinge; with the canal large, deltoid; bilocular within." Pentamerus, Sow. Fig. 210. 211, G. Conchidium, copied from Dalman.

GYROGONA. Lam. A genus of microscopic Foraminifera.

GYROIDINA. D'Orb. A genus of microscopic Foraminifera.

HALIOTIDÆ. Sw. A sub-genus of Calyptræa. Calyptræa dilatata. Sowerby's Genera of Shells, fig. 9.

HALIOTIS. Auct. (αλς, als, sea; ους, ωτος, otos, ear.) Fam. Macrostomata, Lam. Otides, Bl.—Descr. Auriform, broad, depressed, pearly within, rough, costated, tuberculated without; spire short, flat, consisting of one or two whorls; aperture wide; ovate; columella laminar, flat, oblique; a spiral series of perforations running along the dorsal margin.—Obs. The splendid shells belonging to this genus are remarkable for the pearly iridescence of the inner surface, and the row of holes following the course of the spire. The soft parts are eaten in Guernsey and Jersey, and reckoned delicious. They belong to temperate and tropical climates. Fig. 338, H. rubra. 339, Padollus, Montf.

HALIOTOID. (Haliotis and ειδος, eidos, form.) Ear-shaped.

HAMIFORM. (Hamus, a hook.) Curved at the extremity.

HAMITES. Parkinson. (Hamus, a hook.) Fam. Ammonacea, Lam.—Descr. Elongated, cylindrical, chambered, recurved at the smaller extremity, annulated; septa lobed and sinuated.—Obs. This remarkable fossil from the Baculite limestone in Normandy, differs from Baculites in being curved at one extremity, a circumstance from which its name is derived. Some small species are found in Chalk-Marle, Folkstone. Fig. 484*. H. cylindricus.

HARPA. Brug. (Harpa, a harp.) Fam. Purpurifera, Lam. Entomostomata, Bl.—Descr. Oval, ventricose, longitudinally and regularly costated; spire short, with rounded, dome-like whorls; aperture wide, emarginated; outer lip thickened, reflected, composing the last costa or rib; inner lip polished, spread over part of the body whorl, terminating in a point.—Obs. This beautiful genus of shells is so clearly defined by the regular, longitudinal ribs that adorn the external surface, suggesting the idea of a stringed instrument, that there is no danger of confounding it with any other. H. multicostata, (Buccinum costatum, Linn.) and H. ventricosa, are among the most elegant of the testaceous productions of the sea both in form and colouring; the former is rare. The recent species are not numerous, they inhabit the Indian Ocean. A fossil species occurs at Grignon, near Paris. Fig. 419, H. ventricosa.

HARPAX. Parkinson. Part of Plicatula, Auct.

HARPULA. Sw. A group of shells separated from Voluta, Auct. thus described, "shell generally tuberculated or longitudinally ribbed; apex of the spire papillary, smooth, and in general distorted; pillar with numerous distinct plaits; the upper, small and slender, the lower, thickest and shortest."—Type, H. Vexillum. (Voluta, Auct.)

HAUSTATOR. Montf. A genus proposed to include those species of Turritella, Auct. which have angulated whorls.

HAUSTELLARIA. Sw. A sub-genus of Murex, consisting of species with long canal and no spines. Murex Haustellum, fig. 396.

HAUSTRUM. Humph. Purpura, Lamarck.

HELCION. Montfort. A genus composed of species of Patella, which have the apex distinctly and prominently bent forwards. Ex. P. pellucida, fig. 230.

HELENIS. Montf. A genus of microscopic Foraminifera.

HELICELLA. Fer. One of the sub-genera into which De Ferussac has divided the genus Helix, consisting of depressed species with large umbilicus, such as Helix Algira, fig. 279. Gonites Montf.

HELICIFORM. Shaped like shells of the genus Helix.

HELICIGONA. One of De Ferussac's sub-genera of the genus Helix, consisting of angulated species, such as Carocolla Lamarckii, fig. 277.

HELICINA. Lam. Fam. Colimacea, Lam. Ellipsostomata, Bl.—Descr. Globose, compressed, or angulated, generally light and thin; aperture trigonal or semilunar; outer lip thickened and generally more or less reflected; inner lip spread over the body whorl, frequently callous near the columella, which is short, and terminates in a notch, angle, or slight callosity.—Obs. This genus of land shells, distinguished from the genus Helix, by having an operculum and a thickened columellar lip, differs also from Cyclostoma in having the aperture semicircular or angular, the peritreme discontinuous and the operculum concentric. These shells are generally small in size, and simple in form. Lamarck describes only three or four species. Mr. Gray described some others in the Zoological Journal, and in a work shortly to be published by the author, a monograph of the genus will contain descriptions and figures of at least 60 distinct species; some of which have been lately brought to this country by Mr. Cuming from the Philippine Islands. They mostly belong to tropical climates.

HELICITES. Bl. Part of the genus Nummulites, Lam. Rotalites and Egeon, Montf.

HELICOGENA. Fer. A sub-genus of Helix, consisting of species, which, like the common garden snail, fig. 268, are globose and simple in form.

HELICOLIMAX. Fer. Vitrina, Drap. H. Pellucida, fig. 263.

HELICOPHANTA. Fer. A sub-genus of Helix, consisting of ear-shaped species with large open apertures.

HELICOSTYLA. Fer. A sub-genus of Helix, consisting of species with numerous whorls, as H. Epistylium, fig. 281.

HELISOMA. Sw. A sub-genus of Planorbis. Sw. p. 337.

HELIX. Auct. Fam. Colimacea, Lam.—Descr. Orbicular, light, generally globular; spire short, last whorl ventricose, aperture oblique, peritreme reflected, interrupted by the most prominent part of the body whorl; columella confluent with the outer lip, and contiguous to the axis of the shell. No operculum; a thin epidermis.—Obs. The land shells composing this genus are found in all parts of the world; the common snail, H. Aspersa, is well known as a destructive animal in our gardens. The genera Helix, Achatina, Bulinus, Clausilia, Anostoma, &c., have been united under one generic name by De Ferussac, and again divided under the following sub-generic names, each of which we shall illustrate by a figure. Genus Helix: Sub-genus 1, Helicophanta, consisting of species with large apertures, like Vitrina; Helix brevipes. S. gen. 2, Cochlohydra, Succinea Amphibia, Drap. S. gen. 3, Helicogena, consisting of the common species with the last whorl large; Helix Hæmastoma, H. Contusa, (Streptaxis, Gray,) H. Aspersa. S. gen. 4, Helicodonta, consisting of species with teeth or folds on the columella; Polydonta, Montf. Anostoma, Helix Nux-denticulata. S. gen. 5, Helicigona, Carocolla, Geotrochus. S. gen. 6, Helicella, consisting of depressed species with a large umbilicus; H. Citrina (Naninia, Gray.) S. gen. 7, Helicostyla, consisting of species with a simple aperture, like the Helicogenæ, but with the whorls increasing very gradually; H. epistylium. S. gen. 8, Cochlostyla, Bulinus. S. gen. 9, Cochlitoma, Achatina. S. gen. 10, Cochlicopa, Polyphemus Glans. S. gen. 11, Cochlicella, Bulinus decollatus. S. gen. 12, Cochlogena, Azeca tridens. S. gen. 13, Cochlodonta, Pupa Uva. S. gen. 14, Cochlodina, Clausilia macascarensis, Balea fragilis. The last three sub-genera are included in the genus Odostomia of Fleming. We give an example of each of these sub-divisions, for the sake of presenting the reader with the principal variations to which the genus is subject. The established genera will be characterized in their places. Fig. 254 to 281.

HELIXARION. Fer. Vitrina, Drap. Differing from Helicolimax in the structure of the animal. Fig. 262.

HEMICARDIUM. Cuv. (ἡμισυς, hemisus, half, Καρδια, cardia, heart.) Cardium Hemicardium, fig. 123**, and several similar species.

HEMICYCLA. Sw. A sub-genus of Helix.

HEMICYCLONOSTA—see Cardilia.

HEMICYCLOSTOMATA. Bl. The fourth family of Asiphonibranchiata, Bl. described as "more or less globular, thick, flattened on the under side; spire very short; aperture large, semilunar, entire; its outer edge hollowed; its inner or columellar edge straight, sharp and septiform." This family answers to the genus Nerita of Linnæus, and to the family Neritacea of Lamarck. It contains the genera Natica, Nerita, Neritina, and Navicella.

HEMIMACTRA. Sw. A sub-genus of Mactra, thus described: "General form of Mactra; but the cardinal teeth entirely wanting; cartilage internal, central, in a large triangular cavity; lateral teeth 2/1, distinct, lateral, striated: connected to the Glycimeri. H. gigantea, Lam. v. 472. No. 1. grandis, Sw. Sp. Nov." Sw. p. 369.

HEMIMITRA. Sw. A sub-genus of Paludomus, Sw. (Melanianæ.)

HEMIODON. Sw. A sub-genus of Anodon, described as having "Tubercles or undulations on the hinge margin. H. undulatus, purpurascens and areolata."

HEMISINUS. Sw. A sub-genus of Melania, thus described: "General shape of Melania; but the base of the aperture is contracted and emarginate; outer lip crenated. H. lineolata, Griff. Cuv. xii. pl. 13. fig. 4."

HEMITOMA. Sw. A sub-genus of Emarginula, thus described: "Patelliform; the fissure not cut through the shell, but merely forming an internal groove. H. tricostata, Sw. Sow. Gen. fig. 6."

HEMITROCHUS. Sw. A sub-genus of Geotrochus, Sw. H. hæmastoma. Sw. p. 331.

HEPTALASMIS. Leach. (Ἡπτα, hepta, seven; ελασμα, elasma, plate) A small shell resembling Pentelasmis, from which it differs in the number of valves, being composed of seven valves according to Leach, and of eight according to Gray, who counts the dorsal valve, which is jointed, as two, and names his genus Octolasmis. Fig. 41, H. Warwickii.

HERCOLES. Montf. A microscope shell, appearing from De Montfort's figure to resemble Trochus Imperialis in shape.

HERION. Montf. Lenticulina, Bl. Microscopic.

HERMAPHRODITA. Bl. The third sub-class of Paracephalophora, Bl. divided into, Sect. 1, symmetrical, containing the orders Cirrobranchiata and Cervicobranchiata; Sect. 2, non-symmetrical, order, Scutibranchiata.

HERMES. Montf. A genus composed of Conus Nussatella, Auct. and other elongated, cylindrical, striated species. Fig. 460.

HETEROBRANCHIATA. Bl. The fourth order of the class Acephalophora, Bl. containing no testaceous mollusca.

HETEROPODA. Lam. The fifth order of the class Mollusca, Lam. This order contains but one genus of shells, viz. Carinaria, fig. 488.

HETEROSTEGINA. D'Orb. A genus of microscopic Foraminifera.

HIATELLA. Daud. Fam. Lithophagidæ, Lam. A genus composed of species of Saxicava, Auct. which have sharp, angulated, posterior ridges, a circumstance which occurs to many species in a young state, which afterwards become rounded off. Fig. 95, Hiatella biaperta.

HIATULA. Sw. A genus proposed to include those species of Oliva, Auct. which have widened apertures. Ex. O. Subulata, fig. 458.

HIBOLITHES. Montf. A genus composed of species of Belemnites, Auct. which are swelled towards the apex, and contracted near the centre. B. Hastatus, Auct. fig. 468.

HIMANTOPODA. Schum. Malleus, Auct.

HINGE. The edge of the bivalve shells near the umbones, including the teeth and ligament.

HINNITES. Defr. A generic name proposed for Pecten Pusio, Auct. remarkable for the irregularity of the outer surface, which would almost lead to the belief of its being an attached shell. Fig. 173, H. Pusio.

HIPPAGUS. Lea. (Horse boat.) A minute fossil shell, resembling Isocardia in form, but destitute of hinge teeth. H. Isocardioides, fig. 128.

HIPPOCHRENES. Montf. Species of Rostellaria, Auct. with the outer lip spread. Fig. 403. R. Columbaria.

HIPPONYX. (Ἱππος, hippos, horse; ονυξ, onyx, nail or hoof.) Fam. Rudistes, Lam.—Descr. Inequivalve, sub-equilateral, rather irregular, destitute of ligament and hinge teeth; lower valve attached, flat, sub-orbicular, with a muscular impression, composed of two lunulate portions, meeting at one extremity, and presenting the form of a horse-shoe; upper valve conical, with the apex inclined backwards, and the muscular impression marginal.—Obs. The earlier naturalists having only met with the upper valve of these shells, placed them among the patelliform univalves; to some of which, particularly Pileopsis, they bear a very strong resemblance. The species of Hipponyx are numerous, and till lately only known in a fossil state. The recent species belong to tropical climates: the fossil species are found in the tertiary beds. Fig. 199, H. Cornucopia.

HIPPOPODIUM. Conybeare. Fam. Cardiacea, Lam.—Descr. Equivalve, obliquely transverse, heavy, deep, inequilateral, umbones incurved; ventral margin sinuated, so as to give a bilobed appearance to the shell; hinge incrassated, with one rugged oblique tooth.—Obs. These fossils are found in the upper beds of Lias. Fig. 129, H. Ponderosum.

HIPPOPUS. Lam. (Ἱππος, hippus; πους, pous, foot.) Fam. Tridacnacea, Lam.—Descr. Equivalve, inequilateral, regular, subquadrate; lunule closed, flat, with crenulated edges; ventral margin deeply undulated; external surface fluted, with radiating ribs, which are transversely fringed with rows of tubular spines; hinge margin thick, with two long, compressed posterior lateral teeth in one valve, three in the other; ligament marginal, external.—Obs. The shell thus described is rightly separated from Tridacna, on account of the anterior dorsal margins being closed; whereas in Tridacna there is a wide hiatus. Only one species of this genus is known, which receives its name from its resemblance in form to a horse's foot, when held with the flat anterior dorsal margin downwards. Few shells are found to concentrate so many beauties as the Hippopus Maculatus, commonly called the Bear's-paw-clam; the delicate whiteness of the interior, the undulating edge, the radiated fluted columns, adorned at intervals by crisped fringes, and the richness of the variegated colouring, are such as to secure the admiration of the most superficial observer. From the Indian Archipelago. Fig. 156, H. Maculatus.

HIPPURITES. Montf. Fam. Orthocerata, Lam. Rudistes, Bl.—Descr. Tabular, rude, irregular, attached; lower valve cylindrical, more or less lengthened, apparently divided into sections by septa (considered by some authors as merely projecting layers of growth) having one or two lateral tubes within; upper valve round, flat, fixed on the aperture of the tubular valve like an operculum.—Obs. This genus is known only in a fossil state, and but very imperfectly. Lamarck places it among his chambered Cephalopoda, &c. De Blainville, considering it a true Bivalve, enumerates it among his Rudistes. Cretaceous group. Fig. 198, H. Cornucopia.

HORTOLUS. Montf. Spirolina, Lam. Microscopic.

HYALÆA. Auct. (Hyalus, glass.) Fam. Pteropoda, Lam. Thecosomata, Bl.—Descr. Globose, glassy, transparent, with a triangular opening at the upper part where the dorsal portion advances beyond the ventral; ventral portion vaulted; dorsal more flat; lower extremity tridentate.—Obs. The singular structures composing this genus were formerly taken for bivalves, and named Anomia Tricuspidata, &c. They are now known to belong to the class of molluscous animals, called Pteropoda, from the wing-shaped organs of locomotion. A species of Hyalæa occurs in Sicily in a fossil state. Recent species are found in the Mediterranean, Atlantic, and Indian Oceans. Fig. 226, H. Tridentata.

HYALINA, Studer. Vitrina, Drap.

HYALINE. (Hyalus, glass.) Glassy, thin, transparent—Ex. Carinaria Mediterranea, fig. 488.

HYDROBRANCHIATA. Bl. The first section of the order Gasteropoda, Lam. containing Molluscs which breathe water only; divided into the families Tritoniana, Phyllidiana, Semi-phyllidiana, Calyptracea, Bullæana, and Aplysiana.

HYGROMANES. Fer. A sub-division of Helix, containing H. limbata, Auct. &c. Gray's Turton, p. 143.

HYRIA. Lam. A genus composed of species of Nayades, distinguished by their alated dorsal margins, and lamellated lateral teeth. South America. Hyria corrugata, fig. 143, Hyria Syrmatophora, fig. 144.

HYRIDELLA. Sw. A genus of "Hyrianæ," Sw. described as differing from Hyria, Auct. in having a cardinal as well as a lateral tooth in each valve. Sw. p. 380.

HISTRIX. Humph. Ricinula, Auct.

JANERA. Schum. A genus composed of species of Pecten, Auct. having oblique plicæ or calli on each side of the ligamentary pit. Ex. P. plica, fig. 172. Decadopecten, Rüppell.

JANTHINA. Auct. (Janthum, a violet.) Fam. Neritacea, Lam. Oxystomata, Bl.—Descr. Sub-globose, thin, fragile; spire short, consisting of few whorls; aperture angulated, at the anterior junction of the inner and outer lips; columella tortuous, contiguous to the axis; outer lip thin, sinuated in the centre.—Obs. The shells composing this genus are celebrated for their beautiful purple colour. The animal possesses a small vesicular process, which keeps it floating on the surface of the water; it exudes a purple secretion when irritated. It is occasionally floated on to the shores of most temperate and tropical countries. Fig. 333, J. Fragilis.

JATARONUS. Adanson. Chama, Auct.

IBERUS. Montf. Carocolla, Lam.

IBLA. Leach. Fam. Pedunculated Cirripedes, Lam.—Descr. Four valves, posterior pair elongated, anterior pair short, triangular; pedicle cylindrical, contracted at the base, hairy.—Obs. I. Cuveriana (fig. 40) is brought from Kangaroo Island.

ICTHYOSARCOLITES. Desmarest. Fam. Ammonacea, Lam.—Descr. Chambered, slightly arcuate, laterally compressed; septa simple, leaving triangular articulations imbricated like the thick muscles of a fish.

JESITES. Montf. A minute fossil resembling Galeolaria.

ILOTES. Montf. Orbiculina, Bl. A genus of microscopic Foraminifera.

IMBRICARIA. Schum. Conohelix, Sw.

IMBRICATED. (Imbrex, a tile.) A shell is said to be imbricated when the superficial laminæ are arranged over each other in the manner of tiles.

IMPERATOR. Montf. A genus composed of species of the genus Trochus, Auct. with whorls angulated and stellated, having an umbilicus. Ex. T. Imperialis. Some of the shells named Imperator in the British Museum belong to the genus Calcar, Montf. having no umbilicus.

IMPRESSION. See Muscular Impression.

INCRASSATED. (Crassus, thick.) Thickened, as the hinge of Glycimeris, fig. 67.

INCURVED. Turned inwards or bent forwards. Applied to symmetrical shells, when the point of the apex turns towards the anterior extremity, as in Patella. The apex of a shell is said to be incurved when it is bent inwards, but not sufficiently so to be described as spiral. Ex. Ammonoceras, Lam. fig. 477.

INDENTED. (In, in; dens, a tooth.) Exactly the reverse of Dentated; meaning a series of small cavities, such as might be produced by the entrance of teeth. The cast of a dentated surface would be indented.

INEQUILATERAL. (Æquus, equal; latus, a side.) A term applied to a bivalve shell when its extent on one side of the umbones is greater than that on the other. When the sides are nearly equal, the term sub-equilateral is used.

INEQUIVALVE. (in; æquus, equal; valva, valve.) The two principal valves differing from each other in diameter or convexity.

INFERIOR VALVE is that which is attached to sub-marine bodies. Only applied to attached bivalves.

INFEROBRANCHIATA. Bl. The fourth family of the second section of Paracephalophora Monoica, Bl. containing no testaceous mollusca.

INFLATED. Swelled, as Bulla, fig. 250, 252. This term can only be applied to rotund shells of a light, thin texture. In other cases we should use the word Ventricose.

INFLECTED. Turned inwards. This term is applied to the outer lip of a spiral shell when it turns towards the body whorl. This is the case in Cypræa, fig. 446. See Reflected.

INFUNDIBULUM. Montf. (A funnel.) A genus formed of those species of Calyptræa, Lam. which, having a spiral septum, so nearly resemble Trochus that some authors have placed them in that genus. One species named Patella Trochiformis. Recent from South America, fossil from the tertiary beds. Fig. 237, 238, Calyptræa (Infundibulum) Pileus.

INNER LIP. That edge of the aperture of an univalve shell which is near to the imaginary axis, as distinguished from the outer lip, or that which is on the opposite side.

INOCERAMUS. Sow. Fam. Malleacea, Lam. Margaritacea, Bl.—Descr. Thick, inequivalve, sub-equilateral, triangular, deep, with the umbones incurved; hinge formed of a series of transverse grooves.—Obs. The larger valves of these fossil shells resemble the larger valve of Gryphæa; but the hinge is quite distinct. The species described in Mineral Conchology are found in the blue marl, at Folkstone, and in the chalk. I. Lamarckii, (Catillus, Brong.) fig. 167.

INTERNAL CAST. The mould of a fossil shell, composed of matter which entered the shell in a soft state, and has subsequently hardened, when, the shell dropping off, the hardened substance which filled it is left to represent its internal form.

INTERNAL LIGAMENT. A term used by some conchological writers signifying that the ligament of a bivalve shell is placed within the closed part of the hinge, so as not to be seen when the valves are shut. But the substance, formerly called the internal ligament, is now distinguished from the true ligament both in structure and use; and is now more properly called the cartilage, so that when the ligament is said to be internal, it must be understood that the internal cartilage is unaccompanied by any ligament properly so called, and when a shell is described as having two ligaments, as in the case of Amphidesma, it means that the two substances are so far removed from each other in the hinge that they are no longer confounded together.

INTERNAL SHELL is one which is enclosed in the soft parts of the animal, as a bone is enclosed in the flesh of a human body. The Limax, or common garden slug, which has a testaceous shield beneath its mantle, is an instance of this.

IO. Lea. A genus composed of several species of fresh-water shells which are considered as differing from Melaniæ in having the anterior termination of the aperture produced into a point in some degree resembling the caudal canals of shells belonging to the family of Canalifera, which are marine. Io fusiformis and spinosus are described and figured in Lea's work on the genus Unio.

JODAMIA. Defr. A genus resembling Birostrites, except that in Jodamia one valve overwraps the other, while in Birostrites the circumference of the valves is equal.

IPHIGENIA. Gray. A sub-genus of Clausilia, C. biplicata, &c. Auct. Gray's Turton, p. 214.

IRIDEA. Sw. A genus of "Hyrianæ," Sw. thus described:—"Oblong ovate; bosses small, depressed, sulcated; inner cardinal tooth placed beneath the outer. I. granosa, Lam. En. Méth. 248. fig. 9."

IRIDINA. Auct. A genus belonging to the Nayades, and resembling the Anodontæ, Auct. but its peculiar characteristic is that the hinge lamina is tuberculated or crenulated in its whole length. Sowerby unites all the genera of the family into the genus Unio. Fig. 150, I. Elongata.

IRREGULAR SHELLS, are those which, being attached to, or imbedded in other marine bodies, have no constant form, but are modified in shape according to the substances to which they are fixed, as the Chamacea, fig. 153 to 155.

IRUS. Oken. Comprehending Pandora, Petricola, Saxicava, &c.

ISOCARDIA. Lam. (Ισος, isos, similar; Καρδια, cardia, heart.) Fam. Cardiacea, Lam. Chamacea, Bl.—Descr. Cordiform, regular, equivalve, ventricose, with distant, diverging, involute, free umbones; hinge with two compressed cardinal, and one distant, compressed lateral teeth in each valve; ligament external, bifid, diverging in the direction of the umbones.—Obs. The shells composing this genus are remarkable for the beautiful curvature of the diverging umbones. European and Chinese Seas. Fig. 126, I. Moltkiana.

KEEL. A flattened ridge, resembling the keel of a ship. As that on the back of Carinaria vitrea, fig. 488, and those on the whorls of some spiral shells. A shell characterized by a keel or keels is said to be carinated.

KELLIA. Turton, Mya Suborbicularis, Montague.

LABIS. Oken. Monodonta, Lam.

LABIUM, or inner lip,—is used to express that side of the aperture which is nearest to the axis and generally contiguous to the body whorl. The lower part of this, when sufficiently distinct from that part which overwraps the body whorl, is called the Columella.

LABRUM, or outer lip,—is the edge of the aperture at the greatest distance from the axis.

LACINEA. Humph. Chama, Lam.

LACUNA. Turt. Fam. Turbinacea, Lam.—Descr. Globose, thin, covered with a smooth epidermis; spire short, consisting of few rapidly increasing whorls; aperture semilunar, rounded at the extremities; columella oblique, reflected over part of the umbilicus; umbilicus forming a lengthened area behind the columella. Northern shores. Fig 364, L. Pallidula.

LAGENULA. Montf. A genus of microscopic Foraminifera.

LAMELLATED. (Lamella, a thin plate.) When the layers of which a shell is composed, instead of being compacted into a solid mass, are separated, overlying each other in the manner of tiles, with the edges prominent, the structure is said to be lamellated or foliaceous.

LAMELLIBRANCHIATA. Bl. The third order of the class Acephalophora, Bl. consisting of bivalve shells, divided into the families Ostracea, Subostracea, Margaritacea, Mytilacea, Polydontes, Submytilacea, Chamacea, Conchacea, Pylorides, Adesmacea.

LAMELLIPEDES. Lam. (Lamella, a thin plate, pes, a foot.) The third section of the order Conchifera Dimyaria, containing bivalves, with the foot of the animal broad and thin; divided into the families Conchacea, Cardiacea, Arcacea, Trigonacea, Nayades. Fig. 111. to 152.

LAMPAS. Montf. Lenticulina, Bl. A genus of microscopic Foraminifera.

LAMPRODOMA. Sw. A genus of "Olivinæ," Sw. thus described:—"Mitriform; spire produced, conic; resembling Mitrella in shape, but the suture is channelled; the aperture effuse at the base, contracted above; lower half of the pillar with 6 to 7 plaits. Volutella, Zool. Ill. ii. series, pl. 40. f. 1. (fig. 86. )" Sw. p. 321.

LAMPROSCAPHA. Sw. A sub-genus of "Anodontinæ," Sw. thus described:—"Shell not winged, elongate, pod-shaped; teeth none; bosses near the anterior extremity. Tropical America only? L. ? elongata. Sw. Zool. Ill. i. 176. ensiforme, Spix. Braz. Test. siliquosa. Braz. Test. pygmæa. Ib." Sw. p. 381.

LAMPROSTOMA. Sw. A sub-genus of Canthorbis (Trochus), described at p. 350, Lardn. Cyclop. Malac.

LAMPUS. Humph. Terebratula, Lam.

LANCEOLATE. Lengthened like a lance.

LANISTES. Montf. Reversed species of Ampullaria, fig. 319.

LAPLYSIA. See Aplysia.

LAPLYSIACEA. Lam. (properly Aplysiacea) A family belonging to the first section of the order Gasteropoda, Lam. containing the genera Aplysia and Dolabella. Fig. 254, 255.

LARVA. Humph. Fissurella, Lam.

LATERAL. (Latus, a side.) The lateral teeth are those which, taking their rise near the umbones, proceed to some distance towards the sides of the shell; as distinguished from the cardinal teeth, which receive their full developement close to the umbones. Lateral muscular impressions are those which are placed at a distance from each other, on the opposite sides of the shell.

LATIAXIS. Sw. A genus of "Eburninæ," Sw. corresponding with the genus Trichotropis. Sow. (Sw. Malac. p. 306.)

LATIRUS. Montf. A genus composed of species of Fusus, Auct. which have an umbilicus and are turriculated.

LAURIA. Gray. A sub-genus of Pupa, containing P. umbilicata, &c. (Gray's Turton, p. 193.)

LEGUMINARIA. Schum. A genus composed of species of Solen, Auct. which have an internal longitudinal bar or rib. Fig. 61. S. Radiatus, Lam.

LEILA. Gray? Described as having the hinge edge smooth like Iridina, but having a "sharp siphonal inflexion." (Syn. B. M. p. 142.)

LEIODOMUS. Sw. A genus of "Buccininæ," Sw. consisting of Terebra vittata and other similar species. This genus corresponds with Bullia, Gray.

LEIOSTOMA. Sw. A genus of "Fusinæ," Sw. thus described, "Equally fusiform," (with Fusus) "but ventricose in the middle; shell entirely smooth, almost polished; inner lip thickened, and vitreous; base of the pillar very straight. Fossil only. (fig. 75.) L. bulbiformis. En. Méth. 428. f. 1."

LEMBULUS. Leach. A genus composed of oval species of Nucula, resembling N. margaritacea, fig. 137.

LENDIX. Humph. Pupa, Lam.

LENGTH. See Measurement.

LENTICULAR. (Lens.) Of a circular, convex form, as Pectunculus, fig. 134.

LENTICULINA. Lam. A genus of microscopic Foraminifera.—Descr. Lenticular, sub-discoidal, compressed, convolute, symmetrical; aperture notched; chambers few in number; visible on the exterior, radiating from the centre of the disk.

LEPADICEA. Bl. The first family of the class Nemantopoda, Bl. This family consists of the same animals which constitute the Pedunculated Cirripedes of Lamarck, and part of the genus Lepas in the system of Linnæus. It contains the genera Gymnolepas, Pentalepas, Polylepas and Litholepas.

LEPAS. (Λεπας, lepas, a rock.) The Linnæan name Lepas contains all the Cirripedes or Multivalves, the different kinds of which are not distinguished in the accounts given by early writers of the habits of the animals. (Fig. 14 to 43.) It was formerly applied to the Limpets or Patella. In fact, the ancient definition was "Concha petræ adhærens," and would apply to any shells attached to rocks.

LEPTÆNA. Dalman. A genus belonging to the Brachiopoda; and thus described:—"Hinge compressed, rectilinear, frequently exceeding the width of the shell." It forms part of the genus Producta, Sow. Fig. 206, L. depressa.

LEPTOCONCHUS. Rüppell. (Λεπτος, leptus, thin; Κογχος, conchos, shell.) This shell resembles a young Magilus in general appearance, although the animal is said to differ. In the young Magilus also, the inner lip is reflected over the body whorl, which is not the case in Leptoconchus. Red Sea. Fig. 11.

LEPTOCONUS. Sw. A sub-genus of Conus, consisting of Conus grandis, amadis, duplicatus, Australis, &c. Sw. p. 312.

LEPTOLIMNEA. Sw. A sub-genus of Limnea, described as being nearly cylindrical. Limnea elongata, Sow. Gen. fig. 6.

LEPTON. Turton. Solen Squamosus, Montague, and other species described as "flat, nearly orbicular, equivalve, inequilateral, a little open at the sides. Hinge of one valve with a single tooth, and a transverse linear lateral one on each side; of the other valve, with a cavity in the middle and a transverse deeply cloven lateral tooth each side, the segments of which divaricate from the beak." To represent this genus we have figured L. Squamosum in the plates, fig. 62. British.

LEPTOSPIRA. Sw. A sub-genus of Bulinus, thus described: "Spire excessively long, sub-cylindrical; body whorl largest; outer lip thickened; aperture oval; no teeth, striata, Sw. Chem. 135. f. 1226. signata Sw." Sw. p. 335.

LEUCOSTOMA. Sw. A genus of "Achatina," Sw. described as resembling Achatinella, but having a "thick pad" at the top of the "upper lip," and another over the base. L. variegata, Sw. Lardn. Cyclop. Malac. fig. 24. p. 172.

LEUCOTUS. Sw. A sub-genus of Natica, described as intermediate between Sigaretus and Lacuna. Sigaretus cancellatus, Lam. (Sw. Malac. p. 346.)

LICIUM. Humph. Ovula, Lam. (Ovulum.)

LIGAMENT. (From Ligo, to bind.) The true ligament is always external, and serves the purpose of binding the two valves of a shell together externally by the posterior dorsal margins. There is another substance, called by Gray the Cartilage, which is elastic and of a condensed fibrous structure, placed within the ligament, either close to it, or at a more interior part of the shell; it is sometimes contained in a pit, formed for its reception, in the centre of the hinge. This substance, being elastic, keeps the valves open, unless drawn together by the counteracting force of the adductor muscles. When conchologists speak of a shell as having the ligament external, the real meaning is that these two substances are so close together as in appearance to constitute one body placed outside the shell so as to be seen when the valves are closed. When two ligaments are spoken of, as in Amphidesma, the meaning is that the cartilage occupies a separate place on the hinge.

LIGAMENTIFEROUS. (Ligamentum, a ligament, fero, to bear.) Having or containing the ligament, as the cardinal pit in Mya, fig. 71.

LIGULA. Leach. A genus containing the more rounded and less gaping species of Lutraria, Auct. Fig. 77, Lutraria Papyracea.

LIGULATE. (Ligula, a slip, a shoe-latchet.) Thin, slender, like a slip, or neck of any thing, as the anterior muscular impression of Lucina, fig. 104.

LIGUMIA. Sw. A sub-genus of Unio, thus described:—"Very long and pod-shaped; bosses depressed; cardinal teeth moderate. S. recta. Lam. vi. 1. p. 74." Sw. p. 378.

LIGUUS. Montf. A genus containing species of Achatina, Auct. which have rounded apertures and lengthened spires, differing from his Polyphemi, which have lengthened apertures. A. virginea, Auct. fig. 286, is the type of this genus.

LIMA. Brug. (Lima, a file.) Fam. Pectinides, Lam. Subostracea, Bl.—Descr. Equivalve, inequilateral, compressed, oblique-auriculated, oval, radiately ribbed or striated, imbricated, covered with a light brown epidermis; hinge with a triangular disc between the umbones, divided in the centre by a triangular ligamentary pit without teeth; muscular impression one, sublateral, sub-orbicular.—Obs. The shells thus described are marine, two or three species being found on our coasts, and fossil species occurring in Lias, inferior Oolite, Calcaire-grossiér, &c. They differ from Pecten in having a wide hiatus for the passage of a byssus, by which they are occasionally attached, and also in the triangular disc, which separates the umbones. The animal makes use of the valves of his shell as natatory organs, working them like fins or paddles, and by this means proceeding at a rapid rate through the waters. L. Squamosa, fig. 174.

LIMACINA. Cuv. (Limax, a snail.) Fam. Pteropoda, Lam.—Descr. Papyraceous, fragile, planorbicular, sub-carinated, obliquely convolute; spiral side rather prominent, the other side umbilicated; aperture large, entire, not modified, peristome sharp.—Obs. This is Spiratella, Bl. The shell figured as Limacina in Sowerby's Genera, under "pteropoda," is an Atlanta. Our representation of Spiratella Limacinea, fig. 224. is copied from Blainville.

LIMACINEA. Lam. A family of the order Gasteropoda, Lam. including the following

1. Cryptella. Spire mammillated; a septum. Fig. 256.

2. Parmacella. Flat, haliotoid, spiral. Fig. 257, 258.

3. Testacellus. Sub-spiral. Fig. 261.

4. Limax. Incomplete. Fig. 259.

5. Plectrophorus. Conical. Fig. 260.

6. Vitrina. Heliciform, hyaline. Fig. 262, 263.

LIMACINEA. Bl. The third family of the order Pulmobranchiata, Bl. Described as containing shells very variable in form, most frequently inclining to globular or oval; the apex always obtuse; aperture variable, but never emarginated. All the Limacinea are phytophagous and terrestrial. This family answers to the genus Helix of Linnæus and to the Colimacea of Lamarck, leaving out the Auriculacea. It contains the genera Succinea, Bulinus, Achatina, Clausilia, Pupa, Partula, Helix, Vitrina, Testacella, Limacella, Limax.

LIMAX. Lam. Limacinea, Lam. and Bl.—Descr. Internal irregular, sub-quadrate, scutiform, crystalline; apex rounded, indistinct; epidermis, light brown, thin, extending beyond the margin.—Obs. The shell is placed under the scutellum of the common garden slug. Fig. 25, L. Antiquorum.

LIMNACEA. Bl. The first family of the order Pulmobranchiata, Bl. The shells of this family are described as thin, with the outer lip always sharp. It contains the genera Limnea, Physa, Planorbis.

LIMNEANA. Lam. A family of the order Trachelipoda, Lam. containing the following genera:—

1. Limnæa. Spire produced; including Physa. Fig. 308 to 310.

2. Planorbis. Spire orbicular; including Planaria. Fig. 311, 312.

LIMNEA. Lam. (Λιμνας, limnas, lacustrine.) Fam. Limnacea, Lam. and Bl.—Descr. Oblong, light, thin; spire variable in length, acute; last whorl large, aperture large, longitudinal, entire; inner lip spread over a portion of the last whorl; columella forming an oblique fold; outer lip rounded at each extremity, thin.—Obs. These light horn-coloured shells are common in standing pools, ponds and ditches, in various parts of Europe. They resemble the Amber shell (Succinea) in shape, but the animal of the latter is amphibious, and the shell of a bright amber colour. L. Stagnalis, fig. 308. L. auricularia, fig. 309. (Radix, Montf.) The reversed species have been separated under the name Physa, fig. 310. Other generic names have been given to other species.

LINES OF GROWTH. The concentric striæ or lines formed by the edges of the successive layers of shelly matter deposited by the animal by which it increases the shell. The outer edge of the aperture is always the last line of growth.

LINGUIFORM. (Lingua, tongue; forma, form.) Tongue-shaped.

LINGULA. Lam. (Dim. from lingua, tongue.) Fam. Brachiopoda, Lam. Palliobranchiata, Bl.—Descr. Equivalve, oblong, depressed, thin, equilateral, gaping and pointed at the umbones, gaping and truncate or trilobate at the opposite extremities, attached by a fleshy pedicule fixed to the umbones.—Obs. This is the only bivalve shell which is pedunculated, in which respect it constitutes a singular anomaly. The ancient writers, seeing the valves separate, placed it in their systems under the name Patella Unguis. There are several recent species found in the Moluccas, and some fossils in sandy indurated marl, and in alluvium of Suffolk. L. Anatina, fig. 219, is so named from its resemblance to a duck's bill.

LINGULINA. D'Orb. A genus of microscopic Foraminifera.

LINTHURIS. Montf. Conch. Syst. 2. 154. A genus of microscopic Foraminifera.

LIP. See Labium and Labrum.

LIPPISTES. Montf. A genus of microscopic Foraminifera.

LITHODOMUS. Cuv. (Λιθος, lithos, stone; Δωμα, doma, house.) Fam. Mytilacea, Lam.—Descr. Transverse, elongated, cylindrical, equivalve, with the extremities rounded, and the posterior extremity rostrated; umbones not prominent, terminal; hinge straight, destitute of teeth; ligament linear, most conspicuous within; muscular impressions two.—Obs. The shells composing this genus differ from Modiola, not only in the cylindrical form, but also in the circumstance from which the generic name is derived, i. e. of their living in stones. Thus, while the form and structure of the shell bring it near the Mytili or Muscle shells, the habits of the animal cause it to approach the Lithophagi, or rock-eating molluscs of Lamarck. L. Dactylus (fig. 161,) is the Mytilus Lithophagus of ancient authors.

LITHOLEPAS. Bl. (Λιθος, lithos, stone, λεπας, lepas, rock.) De Blainville's name for Lithotrya, Sow.

LITHOPHAGIDÆ. Lam. (Λιθος, lithos, stone; Φαγω, phago, eat or gnaw.) A family of the Conchifera Dimyaria, Lam. consisting of terebrating bivalves, gaping anteriorly, having no accessary valves; and containing the genera Saxicava, Petricola, Venerupis, to which are added other genera enumerated in explanation of figures 91 to 97. Notwithstanding the numerous genera which have been created, I think that the most convenient arrangement will be to reduce them to two, thus—

1. Petricola, with distinct cardinal teeth, including, Clothe, Venerirupis and Coralliophaga. Fig. 91, 92, 97.

2. Saxicava, without teeth, including Biapholius, Hiatella, Sphænia, Byssomya, and Thracia. Fig. 93 to 96.

LITHOTRYA. G. B. Sowerby. (Λιθος, lithos, stone; τρυο, truo, to bore through.) Fam. Pedunculated Cirripedes, Lam.—Descr. Eight unequal valves, forming a laterally compressed cone, the lower central valves being very minute; pedicle fleshy, scaly at the upper extremity; fixed at the base in a patelliform shelly support.—Obs. This genus derives its name from the power possessed by the animal of making dwelling holes in stones or pieces of rock. The remarkable shelly cups at the base of the pedicle is regarded as analogous to the shelly base of the Balanus, so that this genus would form an intermediate link between the Sessile and Pedunculated Cirripedes of Lamarck. Fig. 39, L. dorsalis. West India Islands.

LITIOPA. Ranz. Fam. Turbinacea, Lam.—Descr. "Shell not very thick, horny, with a slight epidermis, rather transparent, conical, with whorls somewhat rounded; the last being larger than all the rest together; with the apex pointed, longitudinally grooved; aperture oval, larger anteriorly than posteriorly, with the lips disunited, the right lip simple, separated from the left by a rather indistinct notch, or a slight emargination in the contour. The left lip slightly reflected backwards, so as to form a kind of salient margin with the anterior extremity of the columella, which is united, rounded, arcuated and slightly truncated at the anterior."—Obs. The Molluscous animals, whose shells are thus described, are found in the Mediterranean, and are remarkable for the power of suspending themselves from the sea-weed on which they live, by a thread resembling a spider's web. The general appearance of the shell presents a medium between Phasianella and Littorina, but it is apparently destitute of an operculum.

LITTORINA. Fer. (Littus, the sea-shore.) Fam. Turbinacea, Lam.—Descr. Turbinated, thick; spire acuminated, consisting of few whorls, about one third of the axis in length; aperture entire, large, rounded anteriorly; outer lip thickened within, acute; columella rather flattened; operculum horny, spiral, with rapidly increasing volutions.—Obs. The shells composing this genus are known from Turbo and Phasianella by the horny operculum; and from Trochus, which has also a horny operculum, by the small number of the whorls. The Littorinæ, among which may be enumerated the common Periwinkle, are, as the name implies, found on sea shores, feeding upon seaweed, in all parts of the world. Fig. 363, L. Vulgaris.

LITUACEA. Bl. The second family of Polythalamacea. Bl. The shells are described as chambered, symmetrical, convolute in part of their extent, but constantly straight towards the termination. The genus Spirula, which is admitted into this family, does not properly belong to it, any more than to the Lituolæ of Lamarck, in which it is also placed. It does not agree with the descriptions of either. This family partly corresponds with the "Lituolées," Lam. and contains the genera Lituola, Ichthyosarcolites, Spirula, Hamites and Ammonoceras.

LITUACEA. Lam. A family of the order Polythalamous Cephalopoda, Lam. containing the genus Spirula, fig. 471.

LITUITUS. Montf. Spirolina, Lam. Microscopic.

LITUOLA. Lam. A genus of microscopic Foraminifera.

LITUOLÆ. Lam. The third family of Polythalamous Cephalopoda, Lam. the shells of which are described as partially spiral, the last whorl continuing in a straight line. The transverse septa which divide the chambers, are in general pierced by a siphon which breaks itself off before it reaches the succeeding septum. This family contains the genera of microscopic Foraminifera Lituola and Spirolina. The genus Spirula, also placed in this family, does not by any means agree with Lamarck's definitions "the last whorl continuing in a straight line."

LITUUS. Humph. Cyclostoma? Lam.

LIVID. (From lividus.) Of a pale, dull, blue colour. The adjective is sometimes used as a specific name. Ex. Conus lividus, Sanguinolaria livida.

LOBARIA. Schum. Sanguinolaria rosea, Lam. (fig. 98) and other similar species.

LOBATE or LOBED. Divided into parts.

LOBATULA. Fleming. A genus composed of two very minute species of chambered shells. Serpula lobata and S. concamerata, Mont. Test. Brit. 515.

LOMASTOMA. Rafinesque. An imperfectly defined genus, probably belonging to the Limnacea.

LONGITUDINAL. Lengthwise. Longitudinal striæ, ribs, &c. are those which radiate from the apex and follow the spiral direction of the whorls, in spiral shells; and from the umbo to the ventral margin in bivalves. The term "decourantes" is employed by French conchologists. The bands in Achatina, fig. 286, are longitudinal or spiral.

LORIPEDES. Poli. A genus composed of species of Lucina, Auct. in which the lunules are not prominent.

LOTORIUM. Montf. A genus composed of species of Triton, Auct. in which the aperture is effuse. T. Lotorium, fig. 400.

LOTTIA. Gray. Patelloida, Quoy and Gaimard.

LUCERNA. Humph. A generic name applied to some species of Helix included in De Ferussac's sub-genus Helicogena.

LUCERNELLA. Sw. A genus of "Lucerninæ," Sw. thus described: "Teeth on both sides of the aperture; surface regularly and distinctly striated. Circumference convex."

LUCIDULA. Sw. A sub-genus of Lucerna, Humph. thus described: "Aperture transverse, both lips much thickened and united; the outer with marginal obsolete teeth at the base; umbilicus closed. Barbadensis, Lam. No. 49. p. 78. Fêr. Moll. pl. 47, 2, 3, 4."

LUCINA. Brug. Fam. Nymphacea, Lam. Conchacea, Bl.—Descr. Equivalve, inequilateral, orbicular, lenticular, radiately striated; hinge with, generally, two minute cardinal teeth, which are sometimes nearly obsolete, and two lateral teeth, on each side of the umbo in one valve, one in the other; ligament external, partly hidden by the margins of the valves when closed. Muscular impressions two in each valve, the anterior one produced into an elongated, ligulate band, the posterior short and semi-rotund; impression of the mantle not sinuated.—Obs. The shells of this genus resemble Amphidesma in general form, but are distinguished by the external ligament, the elongated muscular impression, and the want of a sinus in the palleal impression. East and West Indies, and European shores. Fig. 104, L. Tigerina.

LUNULATE. (Luna, the moon, dim.) Moon-shaped, having the form of a crescent. Applied most frequently to muscular impressions. Semilunar is sometimes used, perhaps with greater accuracy, to express the same shape.

LUNULE. An impression on the anterior dorsal margin of some bivalve shells. The similar impression on the posterior dorsal margin is called the escutcheon.

LUPONIA. Gray. A genus composed of species of Cypræa, Auct. which are described as having the anterior of the columellar lip crossed by several irregular ridges, without any distinct marginal ones, internally narrow, flat; the shell pear-shaped, smooth, or cross-ribbed. Ex. C. Algoensis, Luponia Algoensis, Gray, fig. 447.

LUTRARIA. Auct. (Lutum? mud.)—Fam. Mactracea, Lam.—Descr. Thin, equivalve, inequilateral, transverse, oblong or ovate, gaping at both extremities; hinge with one double and sometimes one single cardinal tooth in each valve, and a triangular, oblique pit with a prominent margin, containing the ligament; muscular impressions distant; palleal impression having a large sinus.—Obs. This genus differs from Mactra in the entire absence or indistinctness of lateral teeth. Fig. 77, L. Papyracea. (Ligula, Leach.) Fig. 78. L. Solenoides. Sandy and muddy shores.

LUTRICOLA. Bl. Lutraria. Lam. Fig. 77, 78.

LYCOPHRIS. Montf. A microscopic fossil described as resembling Nummulites, but having a granulated surface.

LYMNADEA. Sw. A sub-genus of "Mysca," Turton, in the family of Nayades, Lam. thus described: "Posterior hinge margin elevated and winged; the valves connate; the surface smooth. L. alata. Sw. Ex. Conch. (fig. 48.) fragilis. Sw. Zool. Ill. compressa, Lea. Am. Tr. iii. pl. 12. f. 22." Sw. p. 379.

LYMNEA. See Limnea.

LYMNEUS. Lam. See Limneana.

LYONSIA. Turt. Inequivalve species of Anatina, Auct. which have no spoon-shaped cavity in the hinge, but an accessary piece. L. striata, fig. 491, 2.

LYRODON. Goldf. Trigonia?

MACLURITES. Lesuour. Journ. des Scienc. Nat. Philad. t. 1. p. 312. pl. 13. fig. 2, 3.

MACOMA. Leach. Venus tenuis, Bl. and similar species, described as "Clothed with an epidermis; striated, compressed, oval; the summits not very prominent; two bifid teeth upon the right valve and a single undivided one upon the left."

MACRODITUS. Montf. Lenticulina, Bl. A genus of microscopic Foraminifera.

MACROSPIRA. Guild. A genus composed of Helix octona, Auct. Macrospira aperta, Guild.

MACROSTOMATA. Lam. (Μακρος, macros, long; στομα, stoma, mouth.) A family belonging to the first section of the order Trachelipoda, the shells belonging to which are described as haliotoid or ear shaped, with a very large aperture, destitute of an operculum. This family contains the following genera, which maybe thus distinguished.