162 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
ture; periostracum yellowish, rather coarse; hinge of the genus; inner 
margins smooth, interior disk polished, the pallial sinus small, ascending, 
the inner extreme bluntly rounded; muscular impressions distinct, liga¬ 
ment small and weak. Length, 6; height, 5.5; diameter, 2.5 mm. (Dali.) 
Type in U. S. N. M., No. 266158. Type locality, near Cerros Island, 
Lower California. 
Range. Santa Barbara Islands, California, to the Gulf of California. 
Psephidia salmonea Carpenter, 1864. 
Brit. Assoc. Rept. 1864, p. 641. Univ. Cal. Zool. Ptibl., 14; pi. 25, fig. 3. 
Shell very small, ovate trigonal, inequilateral; posterior end evenly 
rounded; posterior dorsal margin rounded; in other ways resembles 
P. tantilla. (Carpenter.) 
Type in Brit. Museum. Type locality, Farallon Islands, California. 
Range. Catalina Island to San Diego, California. 
Psephidia brunnea Dali, 1916. 
Proc. U. S. N. M., 52:413. 
Shell small, rounded triangular, moderately convex, brown, pale yellow 
with zigzag brown reticulation, or even pale yellowish with only traces of 
red or brown on the hingeline; surface apparently smooth, with a dull 
silky effect, which on magnification is seen to be due to minute concentric 
close-set threadlike sculpture; beaks prominent, prodissoconch minute but 
distinct; hinge normal, strong; inner margins entire, pallial sinus shallow, 
irregular. Length, 3.7; height, 3; diameter, 2 mm. (Dali.) 
Type in U. S. N. M. No. 109469. Type locality, Catalina Island, 
California. 
Range. Monterey, California, to San Hipolito Point, Lower Cali¬ 
fornia. 
Family PETRICOLID^. 
Genus PETRICOLA Lamarck, 1801. 
Shell oval or elongated, thin, tumid, anterior side short; hinge with 
three teeth in each valve, the external often obsolete; pallial sinus deep. 
(Tryon. S. S. Conch.) 
Type. Venus lapicida Chemnitz and Gmelin. 
Distribution. United States, France, Red Sea, India, New Zealand, 
Pacific, West America (Sitka to Peru). 
Range in Time. Cretaceous, Pleistocene. 
