204 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Corbula porcella Dali, 1916. 
Proc. U. S. N. M., 52:416. 
Shell small, ashy white, inequivalve, the left valve smaller; inequilateral, 
the posterior end larger; rounded in front, pointed behind; a prominent 
angle separates the posterior dorsal area from the rest of the disk; surface 
concentrically evenly threaded, the threads a little more pronounced on 
the dorsal area; an obscure, almost microscopic, radial striation is some¬ 
times apparent; the siphons protrude beyond the rostrum with a dense 
covering of wrinkled periostracum; interior white, hinge normal, the 
basal margin of the right valve partly overlapping that of the left valve; 
pallial sinus obsolete. Length, 8.5; height, 4; diameter, 4.5 mm. (Dali.) 
Type in U. S. N. M., No. 97039. Type locality. Station 2838, off 
Lower California, in 44 fathoms. 
Range. Santa Rosa Island, California, to Panama. 
Corbula kelseyi Dali, 1916. 
Plate 3, fig. 9. 
Proc. U. S. N. M., 52:416. 
Shell rather large, rounded triangular, whitish, heavy, not inflated; 
the surface sculptured by low concentri-c lamellae, a little more prominent 
near the posterior end of the shell, separated by equal or slightly wider 
interspaces crossed by fine radial threads which do not crenulate the 
lamellae; there is no defined posterior dorsal area or keel; interior with a 
deep anteriorly rounded pallial sinus, fused with the pallial line below for 
the greater part of its length. There seems to be a small, narrow lunular 
area in the left valve. Length, 16; height, 10; diameter of left valve, 
3 mm. (Dali.) 
Type in U. S. N. M., No. 120691. Type locality, Catalina Island, 
California. 
Range. Esteros Bay to Catalina Island, California. 
Genus GRIPPINA Dali, 1912. 
Shell slightly inequivalve, donaciform, small, with a well-marked, 
rounded, ascending pallial sinus; right valve receiving the dorsal edge of 
the left in grooves beneath its own dorsal margins; cardinal teeth two, 
large, sub-equal, prominent, horizontally produced and fitting under the 
beak of the left valve; resilium strong, compressed, situated between the 
two cardinals attached under the beak of the left valve, and having on its 
ventral surface a thin calcareous coating or ossiculum. 
Type. Grippina califarnica Dali. 
Distribution. California. 
