CARD] ID AE 403 



round and slightly gaping at the posterior end. Exterior brownish gray 

 and may be with brown, concentric rings of growth. Interior dull-white. 

 Beaks inflated and high. Ligament large and strong. No lunule or escutcheon. 

 Weak radial ribs seen at both ends only. Concentric growth ridges promi- 

 nent near the margins. Muscle scars and pallial line deeply impressed. Foot 

 of animal large and suffused with heavy, red mottlings. Very commonly 

 dredged in cold, northern waters. 



Genus Clinocardium Keen 1936 

 Clinocardhim ciliatuvt Fabricius Iceland Cockle 



Plate 320 



Greenland to Massachusetts. Alaska to Puget Sound, Washington. 



1/4 to 3 inches in size, a little longer than high, with 32 to 38 ridged 

 radial ribs which are crossed by coarse concentric lines of growth. Exter- 

 nally drab grayish yellow with weak, narrow, concentric bands of darker 

 color. Interior ivory. Periostracum gray and conspicuous. Especially abun- 

 dant from Maine northward in offshore waters. 



Clinocardium nuttalli Conrad Nuttall's Cockle 



Plate 31b 



Bering Sea to San Diego, California. 



2 to 6 inches in length; smaller ones being almost round, adults tending 

 to be higher than long; moderately compressed; commonly with 33 to 37 

 coarse radial ribs which are creased by half-moon-shaped riblets. Older 

 specimens worn smoothish. Exterior drab-gray, with a brownish yellow, 

 thin periostracum. Common offshore. Once called C. corbis Martyn. Known 

 locally as the Basket Cockle. 



Clinocardiimi fucanum Dall Fucan Cockle 



Sitka, Alaska, to oif Monterey, California. 



I to 1/4 inches in length, longer than high, moderately inflated, and 

 with 45 to 50 low, poorly developed, radial ribs which are crossed by mi- 

 croscopic concentric lines. No wavy, radial furrow on the upper posterior 

 edge of the shell. Color whitish with a grayish-brown periostracum. Com- 

 mon in the Puget Sound area. 



Young C. nuttalli are distinguished from this species by their 2 first ribs 

 behind the ligament which are large, rounded and make a wavy edge to the 

 shell. In small specimens of C. ciliatmn, the top edges of the ribs are sharp; 

 in jucanuvi they are rounded. 



