Part 19

CALCAREOUS, (calx, lime.) A term applied to a shell or to its operculum which is composed principally of lime or shelly matter, as is usually the case, in distinction from one which is of an horny, membranaceous texture. The greater number of shells are calcareous, but it forms an important point of distinction with regard to the operculum. The only difference between the genera Trochus and Turbo, as at present established, depends upon the calcareous or shelly, and the corneus or horny texture of the operculum.

CALCEOLA. Fam. Rudistes, Lam. and Bl.--Descr. Equilateral, inequivalve, triangular; umbones separated by a large triangular disc in the lower valve; cardinal margin straight, linear, dentated; lower valve large, deep; upper valve flat, semi-orbicular, forming a kind of operculum to the lower.--Obs. This singular shell, known only in a fossil state, in the Palæozöic beds, is placed by Linnæus in the genus Anomia. Lamarck places it among his Rudistes, but Mr. Sowerby in his genera of Shells, states that it should be added to the family of Brachiopoda. Fig. 194, 195. C. Sandalina.

CALLANTICA. Gray. POLLICIPES hispidus, Leach.

CALLIA. Gray? A genus described as having a peculiarly polished shell like Pupina, but wanting the notch.

CALLISOSTOMA. Sw. A genus of shells separated from TROCHUS, and thus described, "Imperforate; spire elevated, acute; aperture broader than high, transversely ovate, hardly sinuated at the base, and slightly oblique; shells always smooth, and often polished." C. zizyphina is mentioned as an example.

CALLIRHOE. Montf. p. 362, vol. 2. Appears to be figured from the nut or inner portion of a large Belemnite.

CALLISCAPHA. Gray? IRIDINA Nilotica, Sow. Zool. Journ. 1. pl. 2. Separated from Iridina on account of the hinge margin being smooth.

CALLITHEA. Sw. A sub-genus of Mitræ, consisting of those species, which like M. sanguisuga, have the "spire and aperture of nearly equal length; internal channel nearly obsolete; shell with longitudinal linear ribs, crossed by transverse striæ and bands; base contracted." Swainson Mallac. Lard. Cyclop.

CALLOSITY. A term used in general zoology to express those hard horny tumidities formed in the skin of some animals, (such as the Dromedary, for instance) in those parts which are most frequently used. It is not used in this sense by Conchologists, who apply it to those undefined tumidities or bumps which appear on the inner surface and hinge of some bivalve shells, and to the thickening over the umbilicus of Naticæ. Glycimeris, fig. 67. Natica, fig. 327, 328.

CALPURNUS. Montf. OVULUM verrucosum, Auct. Distinguished by the small circular tubercle at the back of each extremity of the shell. Fig. 441.

CALYPTRACEA. Lam. A family belonging to the first section of the order Gasteropoda, Lam., the shells of which are described as always external, covering the animal, and having no operculum. The genera contained in this family may be thus distinguished.

1. CALYPTRÆA. Conical; apex central, septum spiral, cup-shaped, or forked; including Infundibulum. Fig. 234 to 238.

2. CREPIDULA. Apex terminal; septum flat, reaching half across the aperture. Fig. 239.

3. CAPULUS. Conical; apex obliquely curved, no septum. Fig. 240.

4. EMARGINULA. Apex curved backwards; a notch in the anterior margin; including Parmophorus. Fig. 241, 242.

5. CEMORIA. A slit near the apex. Fig. 244.

6. FISSURELLA. A slit upon the apex. Fig. 245.

7. RIMULA. A slit near the margin. Fig. 243.

8. ANCYLUS. Apex curved sidewise. Fig. 246.

CALYPTRACEA. Bl. The second family of the order Scutibranchiata. Bl. thus described: "Shell more or less conical, not spiral, or very slightly so; aperture large and entire." The genera included in this family are Crepidula, Calyptræa, Capulus, Hipponyx, and Notrêma.

CALYPTRÆA. Lam. Fam. Calyptracea, Lam. and Bl.--Descr. Conical, patelliform, irregular, with an internal, lateral, salient plate or septum, varying in form.--Obs. The internal appendage is in some species cup-shaped, in some it juts out of the centre in a double point; in others it is only a small flap; and in others a spiral disc. These last, which are shaped like Trochus, are separated by De Montfort under the appellation INFUNDIBULUM; TROCHATELLA, Sw. The Calyptræa may be known from Crepidula by the septum, which in the latter is a flat plate reaching half way across the cavity. Fig. 234, 5, 6.

CAMERINA. Brug. NUMMULITES, Auct.

CAMILLUS. Montf. A genus founded upon a minute spiral shell, with a triangular aperture, turned over the back of the last whorl. It is figured in Soldani's Testacea Microscopica.

CAMPULOTUS. Guettard. MAGILUS, Auct.

CANAL. A groove which characterizes some spiral univalves, where the inner and outer lips unite at the front part of the aperture. This canal is drawn out in some shells to a considerable length, in others it is turned abruptly over the back. The family Canaliferæ, Lam. (fig. 372 to 401), are all provided with this canal.

CANALICULATED. Applied generally to any distinct groove or canal.

CANALIFERA. (Canalifères, Lam.) A family belonging to the order Trachelipoda, Lam. nearly corresponding with the family Entomostomata in De Blainville's system, and described as having a canal of greater or less extent at the anterior part of the aperture. This canal is sometimes straight, sometimes tortuous, and in some genera it is recurved over the back of the shell. All the shells have an operculum, and the thickness of the perfectly formed outer lip does not increase with age. The Canalifera are characterized by having a canal, in distinction from the Purpurifera, which have only a notch. This family contains the following genera,

1. CERITHIUM. Club-shaped. Fig. 372.