MOLLUSC A. 799 



Solarium LAM. Shell orbicular, conico-depressed, umbilicate, 

 with umbilicus patulous, crenulate or dentate at the internal margins 

 of wreaths. Columella none. Operculum horny. 



Sp. Trochus perspective L., Solarium perspectivum LAM., LISTER Conch. 

 Tab. 636, fig. 24, KCMPH. Amb. Rariteitlc. Tab. 27, fig. L, &c. 



Euomphalus Sow. (fossil genus). 



Bifrontia DESH., Schizostoma BRONN. 



Rotella LAM. Shell orbicular, shining, imperforate. Spire "very 

 short, subconical. Columella callous, convex. 

 Sp. TrocJius vestiarius L., Rotella lineolata, &c. 



Trochus LAM. Shell conical, in some umbilicate, in others 

 imperforate. Aperture transversely depressed, with margins dis- 

 joined above. Columella arcuate, somewhat prominent at the base. 

 Operculum mostly horny, more seldom calcareous. 



Tops. Comp. on the animal of this genus CUVIER Ann. du Mus. xr. 

 pp. 184, 185, Moll., Mem. 16, pp. 15, 16, fig. 13. 



Sp. Trochus solaria L., CHEMN. Conchyl. Tab. 173, figs. 1700, 1701, REEVE 

 Conch. Syst. n. PI. 214, figs, i, 2; Troch. niloticus L., RUMPH. Amb. 

 RariteitTc. Tab. 21, fig. A, Encycl. me'th., Vers. PI. 444, fig. t, &c. Trochus 

 Cookii CHEMN., LAM., LESSON, III. de Zool. PI. 15, from which LESSON 

 forms the genus CooTcia, belongs, according to DESHATES, to Turbo. 



Trochus conchyliophorus BORN., GM., Cuv. R. Ani, ed. ill., Moll. PI. 41, 

 fig. 3. This species causes little stones and pieces of bivalves from the 

 bottom on which it creeps to adhere to its shell ; these foreign bodies in 

 time grow to the shell which thus acquires a very irregular appearance. 

 LAMARCK confounded with this species, from the West Indian Seas, a 

 fossil species from the tertiary formations, which presents the same pecu- 

 liarity, under the name of Trochus agglutinans. Comp. on the fossil species 

 LAMARCK Ann. du Mus. iv. pp. 46 51, vn. PI. xv. figs. 5 7. 



Monodonta LAM., Labio OKEN. 



Delphinula LAM. Shell umbilicate, subdiscoidal or conical, 

 with wreaths rough or angulate. Aperture entire, rotund, some- 

 times trigonal, with convex margins. Operculum horny or calca- 

 reous. 



Sp. Delphinula laciniata, Turbo Delphinus L., RUMPH. Amb. RariteitTc. Tab. 

 20, fig. H, BLAINVILLE Malacol. PI. 33, fig. 3, &c. This genus is scarcely 

 distinguishable from the preceding, but has a circular aperture separate 

 from the columella. 



Turbo L. (in part), LAM. Shell conoid or subturrite, with wreaths 

 rotundate. Aperture entire, rotund, not deformed by the penultimate 



