LI 
and Shells of Massachusetts Bay. 81 
form even slight ridges ; lateral areas in some specimens 
quite distinct, in others almost imperceptible ; margin nar- 
row, coriaceous, coated with a close, short, reddish down, 
irregularly banded with white ; terminal valves semilunate ; 
laminz of insertion crenated and denticulated, lateral bi- 
partite ; connecting ones entire: internally, white at the 
insertion and sides of the valves, deepening towards the 
middle to a beautiful rose color. 
Ozservations. This elegant species, which if equalled, 
is certainly unsurpassed, in the beauty of its’ marking 
and variety of its coloration, by any of the genus, yet 
described, was first found by me in the stomachs of fishes, 
taken near Cohasset rocks; subsequently, considerable 
numbers were procured from the same source, in the vi- 
cinity of Cape Ann; and a single living specimen was ob- 
tained from the rocks on the northeast part of Nahant, at 
low water in July last. 
The only species I know of, bearing much resem- 
blance to this, are C. marmoratus, and C. ruber, Lain. 
"The first is described as black, or greenish, or deep red 
brown, on a lighter ground, and thus far has considerable 
agreement with ours; but the margin is said to be scaly, 
which it is not in ours, and the internal color is greenish, 
in lieu of rose color. The second is described as having 
the back carinate, color an uniform red, sometimes a 
darker streak, on the back, marbled red and white, one 
inch long ; inhabits North Sea ; but the remarkable an- 
gular lines in our species, are too conspicuous in all the 
varieties, to admit of a doubt of its being distinct enough 
from this, notwithstanding their similarity in some re- 
spects. Unfortunately, the figure of C. ruber in Chem- 
'nitz is not accessible; and nothing is said in the descrip- 
tion, of the nature of the margin. 
VOL. II.—NO. 1. 6 
