146 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Type locality, “Mers de California.” 
Range. Bering Strait to Sitka, Alaska. Also Japan. 
Genus PROTOCARDIA Beyrich, 1845. 
Posterior half of the shell radiately striate, anteriorly half distantly 
concentrically striate. (Tryon. S. S. Conch.) 
Type. Cardium hillannm Sowerby. 
Distribution. Universal. 
Range in time. Cretaceous to Pleistocene. 
Protocardia centifilosa Carpenter, 1864. 
Plate 34, figs. 2a, 2b, 2c, 2d. 
Suppl. Rept. Brit. Assoc., p. 642, Univ . Calif., Zool. Publ., 14; pi. 20, figs. 2a-d. 
Shell small, suboval, ventricose, thin; umbones central, prominent, only 
very slightly bent; surface sculptured by numerous fine, close-set, rounded, 
radiating ridges, which are made slightly rugose by numerous fine incre¬ 
mental lines on their surface; thin sharp teeth in each valve; pallial sinus 
shallow, wide; margin beautifully and sharply serrate. Long. 23; alt. 
22.5; diameter, 15 mm. (Arnold.) 
Type locality, Monterey, California. 
Range. Bodega Bay, California, to Lower California. In the Pleis¬ 
tocene at San Pedro and Santa Barbara; Pliocene at Sunol, Alameda 
County; San Pedro, San Diego and Santa Barbara, California. 
Protocardia centifilosa richardsonii Whiteaves, 1878. 
Plate 2, fig. 7. 
Canadian Nat., (2) 8 :469. 
Shell inflated, but not quite as thick as high, inequilateral; outline 
transversely and ovately subcircular, length slightly exceeding the height; 
posterior side rather longer, and more narrowly rounded than the anterior ; 
beaks large, elevated, incurved and approximating; placed a little in ad¬ 
vance of the middle. Surface of the anterior and central portions of the 
shell marked by flattened and comparatively broad, radiating ribs, 
separated by narrower, deeply impressed lines, both of which are crossed 
by faint, concentric striae or lines of growth. On the posterior area the 
radiating ribs are thin, prominent and much narrower than the flattened 
interspaces, and the concentric striations are developed into elevated, thin 
and crenulated laminar ridges. Hinge with two small cardinal and two 
remote lateral teeth in each valve, one of which is sublunular. Pallial 
line entire; inferior margin of the valves denticulated all round within. 
Valves touching at all points when closed; not open at either extremity. 
Length, 8J4 ; height 7j4 ; diameter, 6 lines. (Whiteaves.) 
