140 



CARDIAD^. 



Found plentifully in the stomachs of fish caught in Massachu- 

 setts Bay. Off Ca})e Cod in thirty-five fathoms (^Ativood) ; dredged 

 in Marblehead Harbor, seven fathoms (^Haskell) ; young and dead 

 shells, Grand Manan, common ( Stimpson) ; Eastport ( Cooper, Stmp- 

 son) ; Bedford Basin, Halifax (^Willis) ; Bic and Ramouski, Oulf of 

 iSt. Lawrence (^Bell) ; Cape Hope, James's Bay, 52° 10', dead (Drex- 

 ler Coll.} ; Greenland (Miiller) ; Mingan Island, twenty feet (^Pack- 

 ard) ; Becchey Island {^Belcher}. 



This shell seems not to have been hitherto described, in all its 

 characters, by any one writer. English authors seem to have pos- 

 sessed suj)erannuated 

 specimens, which had 

 lost the epidermis ; and 

 such we have long 

 been in the halnt of re- 

 ceiving from the Bank 

 fishing- grounds. On 

 the other hand, Mr. 

 Couthouy, having only 

 immature specimens, 

 failed to trace their 

 pedigree. Through the 

 kindness of Dr. 8torer, 

 I have had an ojjportu- 

 nity to examine speci- 

 mens of Mr. Couthouy's 

 C. pnbescens of the size 

 above indicated, taken in our bay, covered with their pecidiar 

 epidermis; under which disguise, however, it was not difficult to 

 detect the C. Ishindiann.. A few years since I examined a de- 

 nuded specimen, brought f)y Dr. C. T. Jackson from the coast of 

 Maine, where he says they are not uncommon, measuring two and 

 seven tenths inches in length, by two and four tenths in height. 

 Those taken in Massachusetts Bay seldom exceed half an inch in 

 diameter. 



Destitute of an epidermis, it looks much like C. edule, l)ut is 

 easily distinguished I)y the number of ribs. In two of my speci- 

 mens there are thirty-eight ribs ; in all the others there are thirty- 

 six ; C. edule has twenty-six. It is usually found in company with 

 C. piniiulatum, and small sj)ecimens would not be readily discrim- 

 inated from it. But, besides the greater number of ribs, its bristled 



C. Islandicum. 



