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 Aeephala, 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 



