MARINE MOLLUSCA OF THE UNITED STATES 99 
6. C. Emersonil, Couthouy. Fig. 203. 
Am. Journ. Sci., xxxiv. 217. 1838. 
Chiton vestitus, Sowerby, 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:, Wiz 101, td; 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. (Hur.) 
Distinguished from C. marmoreus by its unpunctured surface. 
OrveER III. OPISTHOBRANCHIATA. 
Section A. TEcTIBRANCHIATA. Animal usually provided with 
a shell, both in the larval and adult state; branchize covered by 
the shell or mantle; sexes united. 
Srecrion B. Nuprprancwiata. Animal destitute of a shell ex- 
cept in the embryo state; branchiz always external, on the back 
or sides of the body; sexes united. 
Section A. 
Family ToRNATELLIDA. Shell external, solid, spiral or convo- 
luted; subcylindrical; aperture long and narrow; columella 
plaited ; sometimes operculated. 
Family Butnipa#. 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 TORNATELLID &. 
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 
