140 



CAEDIAD^. 



Found plentifully in the stomachs of fish canght in Massaehu- 

 setts Bay. Off Cai)C Cod in thirty-five fathoms {Ahvood) ; dredged 

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

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

 son) ; Bedford Basin, Halifax {JVillis) ; Bic and Ramouski, Gulf of 

 St. Lawrence {Bell) ; Cape Hope, James's Bay, 52° 10', dead {Drcx- 

 ler Cull.) ; Greenland {Miiller) ; Mingan Island, twenty feet {Pack- 

 ard) ; Becchcy Island {Belcher). 



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

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

 sessed superannuated 

 ^'°- ^^^- specimens, wliich had 



lost the e])idcrmis ; and 

 such we have long 

 been in the habit of re- 

 ceiving from the Baidv 

 fishing- grounds. On 

 the other hand, j\[r. 

 Couthouy, having only 

 immature specimens, 

 failed to trace their 

 pedigree. Through the 

 kindness of Dr. Storer, 

 I liave had an opportu- 

 nity to examine speci- 

 mens of Mr. Couthouy's 

 C. pubescens of the size 

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

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

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

 nuded specimen, brought by Dr. C. T. Jackson from the coast of 

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

 seven tenths inches in length, ))y 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. cdule, but is 

 easily distinguished by the number of ril)S. In two of my sjjcci- 

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

 six ; C. cdule has twenty-six. It is usually found in com])any with 

 C. pitniiilalKm, and small specimens would not be readily discrim- 

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



C. hlaiidicum. 



