100 CATOPHRAGMUS. 



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 tu- 

 berculated, with a short varicose spire ; aperture long, sometimes 

 narrow, with the outer lip thickened and reflected, generally den- 

 ticulated; 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 Cypr/Ecassis, for 

 reasons which will be stated under the word. Cassidariais distin- 

 guished by the gradual curve of the canal. Fig. 410 is Cassis 

 tuberosa, diminished. 



CASTALIA. Lam. Fam. Trigonees, 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 per- 

 haps 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 Karw, beneath ; typayfiog, a place 



