302 CYPRINID.E. 



taken four or more days before they were brought to 

 me exhibited on dissection the following curious ap- 

 pearance : On removing the mantle from the surface 

 of the shell, a considerable quantity of shelly matter of 

 the consistence of thick cream, or like moistened plaster 

 of Paris, was discovered; on a nearer inspection, the 

 interior layers of its shelly covering were found to be 

 deeply corroded in parallel furrows, in some spots so 

 deeply that the brown or outer layers of the shell were 

 laid bare. This shelly matter had undergone no change 

 but that of trituration. To what cause is this appear- 

 ance to be attributed ? Are the animals of this species 

 when in a state of starvation, as these probably were, 

 capable of absorbing a portion of their shell (the gluten), 

 and converting it into nourishment ? Or do the animals, 

 when languid and unhealthy, secrete a medium that 

 destroys the cohesion of the particles of which their 

 habitations are formed? In none of the living speci- 

 mens that I had an opportunity of examining did I 

 detect any parasite ; while in nine out of ten specimens 

 of the Cyprina Islandica from the same neighbourhood, 

 I found a small Hirudo lurking under the mantle of 

 each ; and in very many specimens of a Modiola from 

 the shallow water of the same coast, a small Crab (Pisa) 

 shared the habitation with the animal." Mr. Bulwer 

 also remarked that the /. cor of the Mediterranean 

 appeared to differ considerably from that of the Irish 

 Sea in respect of the animal, judging from the descrip- 

 tion and anatomical drawings of Poli ; but the differ- 

 ences he has noticed are probably varietal. Mediter- 

 ranean specimens are smaller. Linne indulged in some 

 rather fanciful similitudes with regard to the shell, de- 

 scribing it in the tenth edition of the 'Systema Naturae ' 

 as Cardium humanum, and in the twelfth edition com- 



