130 



CYPRINIDiE. 



ill contact ; anterior part sliorter, 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 })oint ; the space which they include is very 

 coarsely wrinkled ; there is a shallow oval pit before the Ijeaks, l)ut 

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

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

 almost l)lack, coarse and strong, rough with crowded and loose 



Fig. 443. 



C. Ishiadira. 



wrinkles ; hinge-margin In'oad and strong ; cardinal teeth diverging, 

 three in each valve, or rather one large doul)le 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 base sharj) and simple. Length, 

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

 three fourths of an inch. 



This shell is an inhal)itant of all the Northern Atlantic seas, es- 

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

 times thrown up iVom deep water upon our beaches in great num- 

 bers after storms. 'I'lie 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 tlie southward of Massachusetts. 



