52 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
angulated on each side, grooved down the middle; left valve rose-brown, 
obscurely spotted, right valve paler, unspotted; ears equal. (Dali.) 
Type in U. S. N. M. Type locality, San Diego, California. 
Range. Monterey to San Diego; Cortez Bank. In the Pleistocene 
at San Diego, California. 
Subgenus Chlamys Bolten, 1798. 
Pecten hericius Gould, 1850. 
Plate 7, figs. 1, 2. 
Proc. Boston Soc. Nat. Hist., 3:345; Arnold, Tert. Pcctens Cal., pi. 43, figs. 3, 3a. 
Shell triangular ovate, longer than broad, equivalve; valves rather 
full, especially near the beaks, whose sides rise abruptly from the ears; 
color rose-red, paler and zoned with deeper red beneath; everywhere cov¬ 
ered with fine radiating lines, which are rendered rough by erect and 
arched spines. There are about twenty-four radiating ribs. On the upper 
sides these are alternately large and small, the larger ones crowned along 
the ridge by a line of long, erect, hollow spines; on the lower valve the 
ribs are nearly equal, the striae are coarser, and all the ribs are armed with 
a row of spines, though not so long as those on the upper valve; ears 
oblique, very unequal, rayed with coarse, squamous striae. Interior porce¬ 
lain-white, roseate at the edge, where it is finely crenulate. Length, 73; 
height, 65; diameter, 21 mm. (Gould.) 
Type in Boston Soc. Nat. Hist. Type locality, Strait of Juan de Fuca. 
Range. Port Althorp, Alaska, to San Diego, California. 
Pecten (hericius Gould var. ?) albidus Dali, 1906. 
Plate 12, figs. 8, 9. 
Arnold, Tert. Pectens Cal., p. 136; pi. 52, figs. 2, 2a. 
Shell of the same shape and general appearance as P. hericius, but 
smaller when adult, being only about 45 mm. in altitude. The sculpture 
on the right valve consists of numerous elevated, narrow, thread-like, 
imbricated riblets, which have the appearance of being grouped together 
in three or more unequal equidistant, more or less convex fasciculi; the 
interspaces between the fasciculi are ornamented by riblets of equal promi¬ 
nence to those forming fasciculi; anterior ear with about 7 equal, promi¬ 
nently imbricated radials; posterior ear short and with radial and 
imbricating sculpture; byssal notch quite prominent. Left valve similar to 
right, but with the fasciculi corresponding to the interspaces of the right 
valve, and consequently much narrower than the fasciculi of that valve. 
Color white to very light pink. Length, 40; height, 45; diameter, 14 mm. 
(Dali.) 
