CRABS. 



43 



The accompanying illustration, on a very enlarged 

 scale, represents the pinna's companion, Pinnotheres 

 veterum, which will be seen at a glance to differ mate- 

 rially in appearance from P. 2)isum. The mussel is not 



the only shell in which P. 2)isic77i finds ready-furnished 

 lodgings. The common cockle {Cardium edule), and in 

 some instances the ordinary oyster, being selected to 

 supply them. Mr. W. Thompson, in writing on the 

 crustaceans of Ireland, says, " The smallest Pinno- 

 theres I have seen was found by Mr. Hyndman, in a 

 living Cardium exignum, dredged up by us in Strangford 

 Lough, in October, 1834. It is a male. The carapace 

 is under a line in length ; the entire breadth of the 

 Crab from the extremities of the outstretched legs is 

 three lines. The cardium is iinder thxee lines in 

 length, and barely exceeds that admeasurement in 

 breadth ; so that the Crab, when in the position just 

 mentioned, must have on both sides touched the walls 



