Part 23

3. DICERAS. Like Chama, but the umbones free, produced. Fig. 154.

CHAMBERED. When the cavity of a shell is not continuous, but is divided by shelly diaphragms or septa, it is said to be chambered. This is the case with the shells of the Polythalamous Cephalopoda, as in the Nautilus (see Introduction). The character is not confined to these, as it occurs in some species of Spondyli, and in several turrited univalves.

CHAMOSTRÆA. De Roissy. CLEIDOTHÆRUS. Stutch.

CHARYBS. Montf. A genus of microscopic Foraminifera.

CHELIBS. Montf. A genus of microscopic Foraminifera.

CHELINOTUS. Sw. A genus of "HALIOTIDÆ," Sw. including Velutina, Lam. a species of Sigaretus from Tonga, and Coriocella, Bl. Thus described, "Animal cheloniform, broad; depressed; the mantle larger than the shell, lobed in front; tentacula two, short, obtuse; eyes basal; mouth circular; shell ear-shaped, thin, fragile, imperforate; pillar none."

CHELONOBIA. Leach. CORONULA Testudinaria, Auct. Fig. 15.

CHERSINA. Humph. ACHATINA, Lam.

CHICOREUS. Montf. A generic division of the genus MUREX, consisting of such species as have three ramified varices. Ex. M. inflatus, fig. 395.

CHILINA. Gray. Fam. Auriculacea, Bl. Colimacea, Lam.--Descr. Oval, thin, covered with an olive green epidermis; spire rather short, consisting of few whorls; aperture large, oval, rounded anteriorly; outer lip thin, joining the inner lip without a sinus; inner lip spread over part of the body whorl, terminating in a thick columella with one or two folds.--Obs. These shells differ from the true Auriculæ in the thinness of the outer lip. C. Dombeyana (Auricula Dombeyana, Auct.) Fig. 300. The illustrated catalogue published by the author (Sow. Conch. illustr. parts 135, 136) contains 13 species. Rivers of South America.

CHILOTREMA. Leach. A sub-genus of HELIX, containing Helix lapicida, Auct. Gray, Turton, p. 140.

CHIMOTREMA. ----? Belongs to HELIX.

CHIONE. Megerle. CYTHERÆA maculosa, (fig. 117, c.) sulcata, circinata, &c. Auct. and other similar species.

CHIRONA. Gray. A genus of Balanidæ, the shells consisting of six parietal valves and two opercular valves; the upper edges of the parietal valves are sloped and the structure is not tubular.

CHISMOBRANCHIATA. Bl. The second order of the first section of Paracephalophora Monoica, Bl. Those Mollusca belonging to this order which have shells, have them either internal or external, but always scutiform, with depressed spires and wide, haliotoid, oblique apertures, without a columellar lip properly so called. This order partly answers to the family MACROSTOMATA, in the system of Lamarck. It contains the genera Coriocella, Sigaretus, Cryptostoma, Oxinoe, Stomatella and Velutina.

CHITON. Auct. ([Greek: chiton], an integument.) Fam. Phyllidiana, Lam. Class, Polyplaniphora, Bl.--Descr. Oval, consisting of eight arched valves arranged in a series across the body of the animal and fixed in the skin which forms a rim around them, sometimes scaly, spinose, or rugose, sometimes smooth.--Obs. The genus Chiton, commonly called "Coat of Mail," from its resemblance to jointed armour, remains to the present day in exactly the same state with regard to its boundaries as that in which Linnæus found it, and in which he left it. That illustrious Naturalist placed it among the multivalves in his purely Conchological system, although the animal is totally different from the Cirripedes. The shells are prettily marked, and are found attached to the rocks in all seas of Tropical and Southern climates, but fossil species are almost unknown. Fig. 227, C. Spinosus. The genus is divided by Guilding into Chiton, Canthopleura, Phakellopleura, Chitonellus and Cryptoconchus. Zool. Journ. XVII. p. 27. The author of this manual has lately attempted a revision of this interesting but neglected genus, and has given a catalogue of all the species hitherto known, as far as they could be identified among the confused mass of synonyms and descriptions to be found in the works of various Conchological writers. This catalogue is to be found in his Conchological Illustrations, and refers to figures of 102 species, 92 of which are contained in parts 38 to 45, and 159 to 176.

CHITONELLUS. Lam. (From Chiton) Separated by Lamarck from Chiton, on account of the valves being placed at a greater distance from each other, the soft integument of the animal intervening. Fig. 228, C. striatus. Philippines.

CHLOROSTOMA. Sw. A sub-genus of "Trochinæ." Sw. (Trochus) of which C. argyrostoma is given as an example. Sw. Lard. Cyclop. p. 350.

CHONDRUS. Hartmann. ABIDA, Leach. A genus formed for the reception of PUPA secale, Drap. Pupa Juniperi, Montague, which have plaits in the aperture.

CHRYSOAR. Montf. Probably a species of ORTHOCERAS.

CHRYSODOMUS. Swains. "Distinguished from Fusus, by the comparative shortness of the basal channel, and the ventricose or enlarged shape of the body whorl. The beautiful orange-mouthed Whelk of England is a typical example; and the few others now known are all of a very large size, and chiefly found in Northern Seas, where they represent the more elegant Fusi of tropical latitudes; the outer lip is always thin and smooth." Sw. page 90, paragraph 78, described at page 308.

CHRYSOLUS. Montf. POLYSTOMELLA, Bl. A genus of microscopic Foraminifera.

CHRYSOSTOMA. Sw. A genus of the family "Rotellinæ," Sw. Thus described "Shell turbinate; the whorls few and convex; aperture effuse, round; inner lip thickened just over, and almost concealing the umbilicus. Nicobaricus, Martini, 182 fig. 1822-5." Sw. Lard. Cyclop. Malac. p. 327.

CHTHALAMUS. Ranz. Fam. Balanidea, Bl. Order, Sessile Cirripedes, Lam.--Descr. "Shell much depressed, valves thick, thickened at the base, with prominent areas; operculum nearly horizontal, composed of four valves."--Obs. This description would apply generically to the shell called Platylepas in the British Museum, only nothing is said about the prominent plates jutting from the internal surface of the valves. The difference between this genus and BALANUS consists principally in the horizontal position of the operculum, and general flatness of the shell. C. stellatus, fig. 18.

CIBICIDES. Montf. A genus of microscopic Foraminifera.

CIDARIS. Swains. A genus composed of TURBO Smaragdus, petholatus, and other similar species. The word Cidaris is, however, already in use for a genus of Echinæ.

CIDAROLLUS. Montf. A genus of microscopic Foraminifera.

CILIATED. (ciliæ, hairs.) Having minute hairs as in Orbicula, Lingula, &c. and the jointed feelers of the Cirripedes.