MARINE MOLLUSCA OF THE UNITED STATES 99 



6. C. Emersonii, Couthouy. Fig. 203. 



Am. Journ. Sci., xxxiv. 217. 1838. 

 Chiton vestttus, Sowecby, Zool. Journ., iv. 368. 



Shell ovate-oblong, broadest behind ; valves uniform, each 

 with a central heart-shaped area, with bead-like granules or tuber- 

 cles in concentric series round the margin, the remainder covered 

 with a soiled downy membrane ; marginal membrane with series 

 of yellow hairy tufts ; whitish. 



Length 20, width 12.5 mill. 



New England, 



7. C. ruber, Lowe. Fig. 204. 



Zool. Journ., hi. 101, t. 5, f. 2. 

 Shell small, oval, elevated, carinated ; surface smooth under 

 the lens, except the lines of growth ; valves strongly beaked ; 

 light bright red or flesh-color under a blackish pigment ; interior 



bright rose-red. 



New England. (Eur.) 

 Distinguished from C. marmoreus by its unpunctured surface. 



Order III. OPISTHOBRANCHIATA. 



. Section A. Tectibranchiata. Animal usually provided with 

 a shell, both in the larval and adult state ; branchiie covered by 

 the shell or mantle ; sexes united. 



Section B. Nudibranchiata. Animal destitute of a shell ex- 

 cept in the embryo state; branchiae always external, on the back 

 or sides of the body ; sexes united. 



Section A. 



Family Tornatellidje. Shell external, solid, spiral or convo- 

 luted ; subcylindrical ; aperture long and narrow ; columella 

 plaited ; sometimes operculated. 



Family Bullid^. Shell invested by the animal, globular or 

 cylindrical, convoluted, thin, often punctate striated ; spire small 

 or concealed ; aperture long, rounded, and sinuated in front ; lip 

 sharp. No operculum. 



Family TORNATELLIDJE. 



Genus TORNATELLA, Lamarck. 

 Extr. d'un Cours. 1812. 

 Shell solid, ovate, with a conical, many-whorled spire ; spirally 

 grooved or punctate striate; aperture long, narrow, rounded in 



