FAMILY VENERID^ CYPRINA. 215 



FAMILY VENERID^. 



Shells with three cardinal teeth at least, on one valve ; the other having as many or fewer : 

 rarely with lateral teeth; usually solid. Epidermis often scanty or entirely wanting. 

 Tubes elongated, unequal. Foot wide, prominent. Marine. 



Obs. This family corresponds with the Conques marines of Lamarck, and comprises at 

 present four genera. 



GENUS CYPRINA. Lamarck. 



Animal with the edges of the mantle undulated, and furnished with a series of tentacular 

 cirri ; tubes short, separated. Mouth small ; labial appendices small ; gills wide ; foot 

 wide ; compressed, trenchant. Shell obliquely heart-shaped, solid ; beaks prominent. 

 Hinge with three unequal diverging cardinal teeth, and a remote lateral one ; palleal im- 

 pression simple. 



Cyprina islandica. 



PLiTE XXVI. FIG. 26Q (ADULT). FIG. 268 (TOUNQ). 



(STATE COLLECTION.) 



Venus islandica. LiN. Syst. Nut. p. 1131. 



Cyprina id. RussEL, Essex Jour. Vol. 1, p. 37. * 



C. id, Gould, Invertebrata of Mass. p. S2. 



Description. Shelllarge, thick and ponderous, ventricose ; beaks prominent, incurved, con- 

 tiguous. Ligament stout and prominent : basal margin simple, rounded. Cardinal teeth stout 

 and diverging : three in each valve, or the largest one bipartite in the right valve ; lateral tootli 

 inconspicuous : palleal impression distinct. Epidermis coarse and wrinkled. 



Color. Epidermis blackish, becoming olivaceous towards the margin ; interior clialky 

 white ; faint purple on the margin. 



Vertical a.xis, 2'8; transverse ditto, 3'3. Diameter, 1'4. 



It rarely attains a greater size than this specimen, which I derived from Mr. Couthouoy, 

 who obtained it on the norliiern coast. Although a northern shell, it may possibly be detected 

 on the shores of this State. The young shell (fig. 268), which I obtained from fishes, has 

 numerous minute concentric elevated ridges, becoming obsolete on the liighly polished beaks; 

 an obsolete ridge extends from the beaks to the basal margin. It may however prove to be a 

 new species of Astarte. 



