Part 22

CASSIDARIA. Lam. (From Cassis) Fam. Purpurifera, Lam. Entomostomata, Bl.--Descr. Oval, ventricose, spirally grooved and tuberculated, with a short turrited spire and a large aperture, terminating anteriorly in a recurved canal; outer lip thickened, reflected, undulated or denticulated; inner lip expanded over a part of the body whorl and the columella, with part of its lower edge free.--Obs. The recent species of this genus are not numerous; the few fossil species occur in the tertiary strata. C. carinata is found in Calc-grossier and London Clay. In general form this resembles CASSIS, but is at once distinguished by the canal, which does not turn abruptly back, but is slightly curved upwards. ONISCIA (C. Oniscus, &c. Lam.) is distinguished by the shortness of the canal, and the granulated surface of the inner lip. Fig. 407. C. Echinophora. Mediterranean.

CASSIDEA. Sw. (from Cassis.) A genus composed of those species of the genus CASSIS, Auct. which have the "aperture wide; outer lip never broad or flattened, but sometimes slightly inflected; inner lip spreading, but never dilated or detached beyond the base into a prominent rim." East Indies. Ex. C. Glauca, fig. 411.

CASSIDULA. Humph. PYRULA, Auct.

CASSIDULINA. D'Orbigny. A genus of microscopic Foraminifera.

CASSIS. (A helmet.) Fam. Purpurifera, Lam. Entomostomata, Bl.--Descr. Oval or triangular, ventricose, thick, generally tuberculated, with a short varicose spire; aperture long, sometimes narrow, with the outer lip thickened and reflected, generally denticulated; the inner lip spread over the surface of the body whorl, indented and incrassated at its inner edge; canal turned suddenly over the back of the shell. Hab. Seas of tropical climates. The fossil species are rare, occurring in the tertiary strata.--Obs. The large, common species of this well known genus are used for shell cameos and as ornaments on chimney pieces, grottos, &c. and are remarkable for the triangular disc, presented by the inner lip, which, in many species, is thickened and spread over the front of the body whorl and the angulated outer lip. The smaller, more rounded species, which have widened apertures, have been separated by Swainson, under the generic name CASSIDEA. The C. rufa, coarctata, &c. are formed by Mr. Stutchbury into a new genus under the name CYPRÆCASSIS, for reasons which will be stated under the word. Cassidaria is distinguished by the gradual curve of the canal. Fig. 410 is Cassis tuberosa, diminished.

CASTALIA. Lam. Fam. Trigonées, Lam.--Descr. Fluviatile, equivalve, inequilateral, trigonal, with corroded umbones; hinge with two laminar, transversely striated teeth, one of which is posterior, remote from the umbones, short, divided, the other anterior, elongated; epidermis thick; internal surface pearly. Lamarck, in describing this shell, states, that he regards it as intermediate between Trigonia and Unio. It should, however, certainly have been placed in the family of "Nayades," and perhaps should form a part of the genus UNIO itself. C. ambigua, Lam. fig. 140. South America.

CATILLUS. Brong. (A little dish.) INOCERAMUS, Sow.

CATOPHRAGMUS. Sow. (From [Greek: Katô], beneath; [Greek: phragmos] a place paled in.) Order, Sessile Cirripedes, Lam.--Descr. Light principal valves, cemented side by side in a circle; eight small pointed valves beneath, covering the joints of the upper circle, and numerous still smaller valves forming the base of the shell; operculum, four valves.--Obs. This is the only genus of Sessile Cirripedes, consisting of eight principal valves, excepting Octomeris, which is destitute of the accessary pieces from which the genus derives its name. Fig. 23. C. imbricatus. South Africa.

CAUDAL CANAL. The elongated hollow process which terminates the aperture anteriorly of some univalve shells. For instance, Murex Haustellum, fig. 396, has an elongated caudal canal.

CELLANTHUS. Montf. VORTICIALIS, Bl. A genus of microscopic Foraminifera.

CELLULACEA. Bl. The second order of Cephalophora, Bl. consisting of doubtful microscopic bodies, with a number of variously arranged shells, as distinguished from the true Polythalamia, Bl. or chambered shells. See FORAMINIFERA.

CEMORIA. Flemingii. Leach. A small patelliform shell, differing from Fissurella, in having the fissure placed behind the apex, which is produced, pointed and incurved. It is the Patella Fissurella, Müll. Patella Noachina, Chemn. F. Noachina, Sow. Puncturella, Lowe. Fig. 244. Cemoria Flemingii. Scotland and Tierra del Fuego.

CENTRAL. A term used to indicate the position of the muscular impression of a bivalve shell when it is near the centre of the inner surface. It is also applied to the siphon perforating the septum of a chambered shell when it is placed near the centre of the plate. Sub-central is also used as a comparative term, to indicate the position of the siphon, or of the muscular impression, is near the centre. Thus in Placuna (fig. 184), the muscular impression is central: in Exogyra (fig. 183), it is sub-central.

CEPA. Humph. ANOMIA, Linn.

CEPHALOPHORA. Bl. The first class of Malacozoæ, Bl. Divided into: Order 1. Cryptodibranchiata; 2. Cellulacea; 3. Polythalamacea. The first consisting of Cuttle-fish, &c. which are destitute of shells; the second composed of those microscopic cellular bodies, which are regarded as shells by some authors; and the third containing the true chambered shells.

CEPHALOPODA. Lam. (Cephalopodes.) ([Greek: Kephalê], kephale, head; [Greek: pous], [Greek: podos], podos, foot.) The fourth order of the class Mollusca, Lam. containing molluscs, which are characterized by having a series of arms surrounding the head, which is placed above a sack-shaped body. This order is divided into Polythalamia, or many-chambered shells; Monothalamia, or single-chambered cephalopods; and Sepiaria, or cuttle-fish. Fig. 463 to 488.

CEPOLIS. Montf. Belonging to the genus HELIX, Auct.

CERATODES. Guild. ([Greek: Keratôdês], like a horn.) A genus composed of the flat, orbicular species of AMPULLARIA, Auct. which present so near a resemblance to the Planorbes, as to have been considered as belonging to them. Planorbis has, however, a horny texture, and no operculum, and it is always reversed, which may be observed by placing the spire upwards. Fig. 320, represents Ampullaria (Ceratodes) Cornu-arietis.

CERIPHASIA. Sw. A sub-genus of Melanianæ, thus described, "Cerithiform; outer lip thin, dilated at the base; aperture small, slightly emarginate, without any internal groove; inner lip thin. C. sulcata, Sw. fig. 38. p. 204." (Sw. Lard. Cyclop. Malac. p. 342.)

CERITHIUM. Brug. Fam. Canalifera, Lam. Entomostomata, Bl.--Desc. Elongated, ribbed, tuberculated, or rarely smooth, with a lengthened, turrited, pointed, pyramidal spire, consisting of numerous whorls; aperture sub-quadrate, terminated anteriorly by a tortuous canal; outer lip thickened, sometimes reflected, expanded; inner lip thickened posteriorly; operculum horny, spiral, with numerous whorls.--Obs. The fresh-water shells described as Cerithia by Lamarck, are separated under the name Potamis, and may be known by the thick, horny epidermis. Triphora, Desh. has the canal closed, except at the extremities. Cerithium Telescopium, does not appear to present the same characters as the other Cerithia, and has been separated by some writers under the generic name Telescopium. Cerithium Aluco, fig. 372. Mediterranean, East and West Indies, Coasts of the Pacific, Gallapagos, Australia, &c. Some small species are British. Fossils are numerous in the tertiary beds.

CERVICOBRANCHIATA. Bl. The second order of Paracephalophora Hermaphrodita, Bl. containing symmetrical patelliform shells, divided into the families Retifera and Branchifera.

CETOCIS. Montf. Fam. Orthocerata, Lam. and Bl. Placed by De Blainville in his section of Belemnites, characterized as having small folds at the apex. Ex. B. Penicillatus.

CETOPIRUS. Ranz. CORONULA BALÆNARIS, Auct. fig. 16.

CHAMA. Auct. Fam. Chamacea, Lam. and Bl.--Descr. Inequivalve, irregular, thick, foliaceous, attached by the umbo of the lower and larger valve. External ligament placed in a groove, following the curve of the umbones. Umbones spiral, coiled round on the back of the valves; hinge with a thick, crenated, lengthened tooth, in one valve, entering a corresponding cavity in the hinge margin of the other; muscular impressions, two in each valve, distinct, lateral.--Obs. The Linnæan genus Chama, included the beautiful shells now called Tridacna. These are exceedingly different from the true Chama, being regular and unattached. The Chama (Tridacna) gigas, when at its full age and development, is the largest shell known. Specimens have occurred weighing upwards of 500 lbs., and measuring two feet across. Diceras may be known from Chama by the spiral horns into which the umbones are produced; Isocardia, by the regularity of the shells, and it is hardly necessary to mention Spondylus, which may be known by the triangular disc between the umbones; Cleidothærus, Stutch. which resembles Chama in general form, has a separate bony appendage attached to the hinge, and may, moreover, be distinguished by its elongated muscular impression. Fig. 153, C. Lazarus. E. and W. Indies.

CHAMACEA. Bl. The seventh family of the order Lamellibranchiata, Bl. containing the genera Chama, Diceras, Etheria, Tridacna, Isocardia and Trigonia.

CHAMACEA. Lam. A family belonging to the order Conchifera Dimyaria, Lam. described as inequivalve, attached, irregular; with or without a single rough tooth on the hinge; with two lateral muscular impressions in each valve. This family contains the genera--

1. CHAMA. Leafy; umbones spiral. Fig. 153.

2. ETHERIA. Very irregular, pearly, without teeth. Fig. 155.