130 



CYPRINID^. 



ill contact ; anterior part shorter, narrower, rounded and com- 

 pressed ; posterior part full and broad at the back, slightly angular 

 at the extremity ; a very superficial ridge passes from the beaks to 

 the lowest posterior point ; the space which they include is very 

 coarsely wrinkled ; there is a shallow oval pit l^efore the beaks, l)ut 

 no distinctly marked lunule ; the ligament is strong and protuber- 

 ant ; epidermis of a dark, shining, burntr-brown color, sometimes 

 almost black, coarse and strong, rough with crowded and loose 



Fig. 443. 



C. Islandica. 



wrinkles ; hinge-margin broad and strong ; cardinal teeth diverging, 

 three in each valve, or rather one large double tooth and a small 

 one in the right valve; marginal tooth slightly developed, blunt; in- 

 side chalky-white, muscular and pallial impressions superficial, the 

 latter having no sinus ; margin at l>asc sharp and simple. Length, 

 three and a half inches ; height, three inches ; breadth, one and 

 three fourths ()f an inch. 



This shell is an inhabitant of all the Northern Atlantic seas, es- 

 pecially near where some river empties into the ocean. It is some- 

 times thrown u]) from deep water upon our beaches in great num- 

 bers after storms. The young are found abundantly in the stomachs 

 of fishes taken in Massachusetts Bay. It appears not to be com- 

 mon, if it is found at all, to the southward of Massachusetts. 



