252 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
area not raised and poorly defined. Tail valve with mucro much elevated 
and almost overhanging posteriorly, its slope strongly concave. Sutural 
laminae triangular. Girdle covered with minute, short, pointed spinelets, 
with larger scattered spines among them, particularly near the sutures as 
noted above. Color of shell a warm yellowish brown, copiously mottled 
slaty gray. (Berry.) 
Type in Berry Collection. Type locality, off Monterey, California, in 
15 fathoms. 
Range. Known only from type locality. 
Genus OLDROYDIA Dali, 1894 
Valves separated by narrow extensions of the girdle, reaching the 
jugum; jugal area prominent, sculptured differently from the pleural 
tracts and extending in front of them between the sutural laminae; lateral 
areas not differentiated; valves heavy, strongly sculptured. (Dali.) 
Type. Oldroydia percrassus Dali. 
Distribution. California to Lower California. 
Oldroydia percrassa Dali, 1894 
Nautilus, 8:90. Zodlogica, 22, Heft 56, pt. 2, 71; PI. 7. 
Shell solid, strong, small, of a pale pinkish-brown with a darker brown¬ 
ish girdle which appears rather narrow in the dry state; scales very minute, 
partly dehiscent, chaffy, with occasional slender spinules resembling hairs; 
scales on the base crowded, minute, sandy; an extension of the girdle is 
prolonged between the valves on each side as far as the jugum, the surface 
of these sinuses is also minutely scaly with occasional spinules; valves 
thick, white below, moderately arched with the prominent jugum forming 
a sort of keel; near the points of insertion the valves are heavily callous 
below; the sutural laminae are short, smooth, and separated at the median 
sinus by a prolongation of the jugum in advance of the anterior margins 
of the pleurae; sculpture of the jugum consisting of punctate fore and aft 
parallel grooves with some small elevated transverse ridges anteriorly; the 
rest of the valve has, on each side, six or eight vermicular ridges divari¬ 
cating toward the posterior edge of the valve and irregularly corrugated 
with sharp, fine, elevated lamellae crossing the interspaces transversely 
but fading out on the ridges; head-valve with minutely nodulous con¬ 
centric ridges; tail-valve highest at the subcentral, not very prominent 
mucro, in front sculptured like the intermediate valves behind the mucro 
like the head-valve. Length, about 14; width, 5.75; height, 2.5 mm. in the 
dry state. The dry girdle is about half a millimeter wide. (Dali.) 
F854] 
