CARDITIDAE 379 



each other, located nearer the anterior end. Lunule narrow, rough, ill- 

 defined. Numerous strong radial ribs are weakly beaded. Color whitish with 

 a rose tint. Moderately common from i foot to 70 fathoms on sandy bot- 

 toms. Compare with the commoner and closely resembling Venericardia 

 tridentata. 



Genus Venericardia Lamarck 1801 



Shell rounded-trigonal, with strong radial ribs which are commonly 

 beaded; internal margins crenulate; right anterior cardinal and laterals absent. 

 No byssus made. 



Subgenus Cyclocardia Conrad 1867 

 Cyclocardia has whitish shells and a rough periostracum. 



Venericardia borealis Conrad Northern Cardita 



Plate 28t 



Labrador to Cape Hatteras. 



I to i^ inches in height, rounded, obliquely heart-shaped, thick and 

 strong; beaks elevated and turned forward. Surface with about 20 rounded, 

 moderately rough or beaded, radial ribs. Shell white, usually covered by a 

 fairly thick, velvety, rusty-brown periostracum. Lunule small but very deeply 

 sunk. Hinge strong; in the left valve the central tooth under the beak is 

 large, triangular and curved. Very common on the Grand Banks where it 

 serves as a food for fish. 



V. novangliae Morse (Nova Scotia to New York) is similar, but is ovate, 

 the length being slightly greater than the height of the shell. It is sometimes 

 considered a variety of borealis. 



Venericardia ventricosa Gould Stout Cardita 



Plate 29I 

 Puget Sound to Santa Barbara Islands. 



About % inch in length, rounded-trigonal, moderately fat, lunule small; 

 with about 1 3 rather wide, radial ribs which are bluntly beaded. Inner mar- 

 gins of the valves have prominent, squarish, widely spaced crenulations which 

 correspond to the external ribs. There are two other forms, one from Mon- 

 terey (stearnsi Dall), the other from Redondo Beach, which are very close, 

 but their distinctiveness and proper names are yet to be decided. The latter 

 form is V. redondoensis "Burch" P. Morris 1952. C. ventricosa is dredged 

 fairly commonly. 



