CLASS PELECYPODA 
111 
Shell small, transverse, sub-rectangular, inequilateral, ventricose, thick ; 
beaks sub-anterior, not prominent; dorsal posterior margin long, straight; 
anterior portion abruptly truncated just in front of beaks; surface sculp¬ 
tured with heavy, squamose, rounded, radiating ridges; interior margin 
coarsely crenulated; hinge with two lateral diverging teeth in each valve, 
the posterior teeth being in each case much elongated, the anterior short 
and pointed. (Arnold.) 
Type in the California State Collection, No. 403. Type locality, Santa 
Barbara, California. 
Range. Queen Charlotte Islands, British Columbia, to Todos Santos 
Bay, Lower California. In the Pleistocene at Santa Barbara and San 
Pedro, California. 
Genus VENERICARDIA Lamarck, 1801. 
Shell rounded-trigonal, strongly radially ribbed, the ribs frequently 
beaded, especially when young, the lunule minute and deep, the escutcheon 
linear, the internal margins crenate, the hinge with two transversely 
striated cardinals in the left and three in the right valve, the laterals absent 
or obsolete, a sublunular pustule sometimes present in the left valve. 
(Dali.) 
Type. Venericardia imbricata Lamarck. 
Distribution. Chiefly in tropical seas, on rocky bottoms and in 
shallow water. West Indies, United States, West Africa, Mediterranean, 
Red Sea, India, China, Australia, New Zealand. 
Range in time. Eocene to Pleistocene. 
SECTION CYCLOCARDIA Conrad, 1838. 
Venericardia barbarensis Stearns, 1890. 
Plate 43, figs. 9, 11. 
Proc. U. S. N. M., 13:214; pi. 16, figs. 4, 3. 
Shell rounded, inequilateral, variable in outline, more or less oblique, 
moderately convex. Beaks small, slightly elevated and turned forward. 
Surface ornamented with nineteen to twenty radiating ribs usually some¬ 
what granulous, and generally obscure on the extreme anterior and pos¬ 
terior margins of the valves. Epidermis a dingy yellowish-brown, thicker 
toward the ventral margin and sides of the valves thin and commonly 
eroded at or toward the umbos. Lunule small, slightly sunken, faintly 
defined. Hinge line small, not thick; hinge composed of, in the left valve, 
a single strong cardinal sloping posteriorly and a smaller tooth often 
obscure, slanting anteriorly; a third tooth-like process is generally present, 
situated under and apparently a projection of the edge of the lunule. This 
