MOLLUSCA. ° 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 perspectivus L., Solariwm perspectivum Lam., Lister Conch. 
Tab. 636, fig. 24, Rumpu. Amb. Rariteitk. Tab. 27, fig. L, &e. 
Euomphalus Sow. (fossil genus). 
Bifrontia DusH., Schizostoma BRonn. 
Rotella Lam. Shell orbicular, shining, imperforate. Spire very 
short, subconical. Columella callous, convex. 
Sp. Zrochus vestiarius L., Rotella lineolata, &e. 
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. Xt. 
pp. 184, 185, Moll., Mém. 16, pp. 15, 16, fig. 13. 
Sp. Trochus solaris L., CHemn. Conchyl. Tab. 173, figs. 1700, 1701, REEVE 
Conch. Syst. 11. Pl. 214, figs. 1, 2;—Troch. niloticus L., Rumew. Amb. 
Rariteitk.. Tab. 21, fig. A, Encycl. méth., Vers. Pl. 444, fig. 1, &e. Trochus 
Cookiti CuemN., Lam., Lesson, Ill. de Zool. Pl. 15, from which Lesson 
forms the genus Cookia, belongs, according to DESHAYES, to Turbo. 
Trochus conchyliophorus Born., GM., Cuv. R. Ani., éd.ill., Moll. Pl. 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. tv. pp. 46—51, vil. Pl. 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., Rumen. Amb. Rariteith. Tab. 
20, fig. H, BLAINVILLE Malacol. Pl. 33, fig. 3, &e. 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 
