166 AMERICAN MARINE CONCHOLOGY. 
2. G. FASTIGIATA. Gould. 
Bost. Proc., viii. 280. 1862. 
Shell small, obliquely triangular, rather solid, yellowish, concen- 
trically sharply ribbed; apex acute, anterior margin concave, 
dorsal margin arcuate; ventral margin nearly straight, anterior 
angle distinct, posterior angle rounded. 
Length and height 8 mill. 
Frying Pan Shoals, N. Car. 
T have not seen this species, nor has it been figured. 
Genus CARDITA, Bruguiere. 
Encyc. Meth. i. 401. 1789. 
Animal with the mantle-lobes free, except between the siphonal 
orifices; branchial margin with conspicuous cirri; foot rounded 
and grooved, spinning a byssus, labial palpi short, triangular, 
plaited, gills rounded in front, tapering behind, and united 
together, the outer pair narrowest. 
Recent systematists. have separated a number of genera from 
Cardita, and generally, with sufficiently good distinctive char- 
acters; I have indicated these groups in the specific descriptions. 
1. C. BOREALIS, Conrad. Fig. 422. 
Am. Mar; (Conch., 39, t- 8, £1. 183i. 
Cardita vestita, Deshayes, Zool. Proc., t. 17, f. 10. 1852. 
Shell suborbicular, thick, with about eighteen rounded ribs, and 
narrow interstices, concentrically striated; epidermis brownish- 
black; margins crenulated within. 
Length and height 1 inch, diam. .7 inch. 
New York, northwards. 
This is the type of Conrad’s genus Cyclocardia, which also 
includes the following species. 
2. C. Novanaiim, Morse. Fig. 423. 
(Cyclocardia.) First An. Rep. Peabody Acad., 76, f. 1869. 
Shell oblong ovate, thin, beaks nearly central, not prominent; 
with about seventeen ribs and concentric striae; margin crenate 
within. 
Length 21, height 16 mill. 
New England, northwards. 
This species is more transverse and thinner than C. borealis, 
the beaks are not so elevated or projecting, and the hinge-plate is 
much narrower. 
