82 CATALOGUE OF THE MOLLUSCA 



When viewed in a living state there appear to be two siphons 

 at the longer end of the shell, but only the posterior of these has 

 the walls complete ; the other has its anterior side open, formed 

 by a fold in the cloak as in the siphons of the zoophagous 

 gasteropods. The animal has consequently only two pallial 

 apertures. 

 4. M. MABMARATA, Forhes. 



Mt/tilus descors, Mont. Test. Brit. l67. 



Imbedded in the skin of Ascidia tuberosa and A. sordida, (esTpe- 

 cially the former) from deepish water, common. 



86. CRENELLA, Brou-n. 

 1. C. DISCUSSATA, Mont. 



Mytilus decussattcs, Mont. Test. Brit. Supp. 69. 



Crenella elliptica,Bvownsl\\\xst. Rec. Conch. 75, t. 23, f. 12-14. 



In shell -sand at Tynemouth, and the Fern Islands, rare. A 



specimen was got by Mr. King in a cavity of a small stone from 



deep water, brought in by the fishermen. Dredged alive in 



seventeen fathoms off AVhitburn, by Mr. R. Howse. 



This genus undoubtedly comes very near to the costated division 

 of the last ; the crenulated hinge plate, and the deep-seated inter- 

 nal ligament appear to be the chief distinguishing characteristics. 



Family. UNiONiDiE, Fleming. 

 87. ANODON, Cmier. 

 1. A. anatinxjs, Linn. 



Anodon cygneus, var. 8, atiatinus, Gray, Turt. Man. 292. 

 In ponds, frequent. 



Captain Brown figures a specimen from Prestwick Car, which 

 is about six inches in breadth. It has not occurred to us of so 

 large a size. 



88. UNIO, Betzius. 



1. U. picTORTTM, Linn. 



Unio pictorum, Gray, Turt. Man. 295, t. 2, f. 11. 

 Mr. Hogg states that this has been found in the ponds at Wyn- 

 yard, on the authority of Sir W. C. Trevelyan, Bart. It has not 

 been met with further north. 



