CYPRINA. 307 



side ; and through it water is introduced into the vas- 

 cular portion of the foot, when the latter becomes suffi- 

 ciently distended to make a passage in the sand for the 

 whole animal and shell. According to Dr. Johnston it 

 is carnivorous : he states that he once found in its 

 stomach "the undigested remains of a large green 

 Nereis, enveloped in a pulp which was certainly too 

 consistent to have been the sediment from water, how- 

 ever loaded with animalcula." This, however, is so 

 contrary to the known habits of the Acephala, that the 

 admission and detention of the Annelid may be ac- 

 counted for in some other way. Possibly, having 

 entered into the body of the Cyprina, it could not get 

 out, and thus suffered a lingering death. The contrac- 

 tion of the larger tube, or the valve of the smaller one 

 might have prevented its escape in that direction ; and 

 the stomach has no other vent. At any rate, the fact 

 of the Nereis being "undigested" would lead to an 

 inference that such was not the ordinary food of the 

 Cyprina. The same excellent naturalist also remarked 

 that this mollusk and the horse-mussel often swallow 

 the bait of the fisherman. It is true that they are fre- 

 quently caught by the hooks ; but their palps are not 

 prehensile ; and I should be rather disposed to attribute 

 their capture to the fishing-lines being dragged by the 

 tide or the motion of the sea, and to the hooks coming 

 into accidental contact with the gaping shell-fish. C. 

 Islandica is apt to be infested by species of Pinnotheres 

 and Planaria. 



Lister first described this shell. Linne*, and after him 

 Pennant, seem to have confounded it with Venus merce- 

 naria. It is the Pectunculus crassus of Da Costa, and 

 Cyprina vulgaris of Brown. The latter name was adopted 

 by Mr. G. B. Sowerby, in his ' Genera of Recent and 



