192 CARDIIDA. 
other transverse to the anterior border); posterior scar subcir- 
cular, superficial ; pallial line faint, entire. 
CLOTHO, Faujas, 1808. Shell oval,subequilateral; two diverging 
cardinal teeth in each valve. A. Faujasii (exv, 65). Tertiary ; 
Europe. 
CYPRICARDINIA, Hall, 1859. 
Distr.—Silurian, Devonian; New York. (C. lamellosa, Hall 
(exxi, 32). 
Shell elongately trapezoidal, moderately compressed, beaks 
anterior or subanterior, slightly prominent, surface concentric- 
ally lamellated or striated, with a posterior more or less dis- 
tinct dorsal ridge; the ligament appears to have been thin; 
muscular impressions ovate, slightly impressed ; hinge unknown. 
This is a rather unsatisfactorily known palzeozoic genus; the 
shells have the aspect of Cypricardia, but appear to be thinner, 
and nothing is known of their hinge by which their proper clas- 
sification could be decided. 
Famity CARDIIDA. 
Shell regular, equivalve, free, cordate, ornamented with 
radiating ribs; posterior slope sculptured differently from the 
front and sides; cardinal teeth two, laterals 1-1 in each valve; 
ligament external, short and prominent; pallial line simple or 
slightly sinuated behind; muscular impressions subquadrate. 
Animal with mantle open in front; siphons usually very short, 
cirrated externally; gills two on each side, thick, united poste- 
riorly ; palpi narrow and pointed ; foot large, sickle-shaped. 
Carpium, L., 1758. 
Etym.—Kardia, the heart. Cockle. 
Distr.—100 sp. World-wide; from seashore to 140 fathoms. 
Gregarious on sands and sandy mud. Fossil, 330 sp. Upper 
Silurian—. 
Shell ventricose, close or gaping posteriorly ; umbones promi- 
nent, subcentral ; radiately ribbed; margins crenulated ; pallial 
line more or less sinuated. 
Animal with the mantle-margins plaited; siphons clothed 
with tentacular filaments, anal orifice with a tubular valve; 
branchial fringed; foot long, cylindrical, sickle-shaped, heeled. 
The cockle (C. edule) frequents sandy bays, near low-water ; 
a small variety lives in the brackish waters of the river Thames, 
as high as Gravesend, England; it ranges to the Baltic, and is 
found in the Black Sea and Caspian. OC. rusticum extends from 
the Icy Sea to the Mediterranean, Black Sea, Caspian and Aral. 
On the coast of Devon (England) the large prickly cockle (C. 
aculeatum) is eaten. 
