MUSs@isrAND  PECTENS 41 
ously mottled with zigzag lines of white. I have 
found this species living at San Pedro, and at 
times it is abundant as far north as Carmelo Bay, 
near Monterey. 
Pécten davidson, 
Dall, Davidson’s 
Pecten, is represent- 
ed in Figure 21, the 
form and_ sculpture 
of both valves being 
plainly shown. The Pesos ae. 
left valve has twenty-one rounded ribs, while the 
right is nearly smooth. The color is waxen white. 
It was dredged from deep water off Alaska, and 
in Bering Sea. 
Pécten randolphi, Dall, Randolph’s Pecten, was 
obtained by the U. 8. Fish Commission from deep 
water at various stations extending from Bering 
Sea to Mexico. The shell is thin, glossy, and un- 
sculptured, translucent white in color, and meas- 
ures about an inch in diameter. 
Pécten vancouverénsis, Whiteaves, the Van- 
eouver Pecten, is perhaps the smallest member of 
the genus to be found on our coast. The little 
shells are only 5mm. across, and are very fragile. 
Form nearly circular, ribs fine and numerous, 
color very light brown. It has been collected in 
British Columbia, also in San Pedro Bay at a 
depth of two hundred fathoms. 
Pécten ventricosus, Sby., Bulged Pecten, is found 
fossil at San Pedro, but is said to be living from 
Santa Barbara southward. ‘‘P. aequisuleatus re- 
