134 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
ately convex; teeth strong in the right valve, anterior adductor scar narrow 
and rather irregular, elongated, posterior rounded, pallial scar linear. 
Length, 4.3; height, 3.3; diameter, 2 mm. (Dali.) 
Type in U. S. N. M. Type locality, Bering Sea? 
Range. Bering Sea to Coronado Islands, Lower California. 
Rochefortia compressa Dali, 1913. 
Plate 21, fig. 7. 
Proc. U. S. N. M. f 45 :596. Bull U. S. N. M., 112; pi. 3, fig. 1. 
Shell small, thin, glossy, compressed, subovate, inequilateral; beaks low 
pointed, inconspicuous; surface very finely, sharply, evenly, concentrically 
striated; anterior end longer, evenly rounded; posterior more pointed; 
interior polished, the muscular scars perceptible, small; hinge small and 
weak, constructed of two feeble laterals in each valve and a median internal 
resilium. Length, 7; height, 6; diameter, 2 mm. (Dali.) 
Type in U. S. N. M., No. 214445. Type locality, Gulf of California. 
Range. Shumagin Islands, Alaska, to the Gulf of California. 
Rochefortia pedroana Dali, 1899. 
Proc. U. S. N. M. f 21:893; pi. 88, fig. 4. 
Shell large, thin, rounded, rather compressed, white, with a concen¬ 
trically rugose pale-brownish epidermis (to which, in the type adheres a 
good deal of blackish oxide of iron); beaks inconspicuous; surface with 
coarse, concentric, incremental lines; inequilateral; the posterior side short, 
dorsal margins merging roundly into the distal and they into the basal 
margin, which last is nearly straight; hinge feeble, the right anterior 
lamella elongated and very slender; the posterior one shorter and stouter, 
the resilium subumbonal and very small; adductor scars small, the pallial 
scar linear. Length, 9; height, 7.3; diameter, 3 mm. (Dali.) 
Type in U. S. N. M. Type locality, on beach at San Pedro, California. 
Range. Known only from the type locality. 
Rochefortia grippi Dali, 1912. 
The Nautilus , 25:128. 
Shell small, thin, equilateral, ovoid, with a dull brownish periostracum 
more or less encrusted with iron oxide, and sculptured only by feeble 
incremental lines. Beaks inconspicuous, hinge as in the genus, bearing 
two very small diverging cardinals in one valve with a rather strong 
resilium between them which seems to carry a small lithodesma; opposite 
valve edentulous; pallial line entire; inner margins of the valves simple. 
Length, 4.5; height, 2.5; diameter, 1.3 mm. (Dali.) 
