130 CYCLOSTOMA. 



CUV1ERIA. Ranz. (Baron Cuvier.) Class, Pteropoda, Lam. 

 — Descr. Thin, transparent, glassy, cylindrical, rounded and in- 

 flated 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. Mediter- 

 ranean. 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 vivi- 

 parous, and abound in ditches, ponds, slow streams, &c. in 

 Europe and North America. The genus Pisidium has been sepa- 

 rated 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. Ill, C. Rivicola. 



CYCLOBRANCHIATA. Bl. The third order of the second sec- 

 tion of Paracephalophora Monoica, Bl. containing no genera of 

 Testaceous Mollusca. 



CYCLOCANTHA. Sw. A genus of " Trochidse," consisting of 

 Turbo stellaris and T. Calcar, and corresponding with the genus 

 Calcar, Montf. 



CYCLONASSA. Sw. A genus of "Nassinse," 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. In- 

 volvulus, fig. 304, would be the type of this genus. 



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



CYCLOSTOMA. Auct. (kvkXos, cyclos, round ; oro/m, 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 un- 

 interrupted, thickened and sometimes reflected, the operculum is 



