IN THE PLIOCENE DEPOSITS. 105 



an intervening pit for the reception of the larger tooth of the oppo- 

 site valve, and a minute lateral tooth on the posterior slope, with a 

 very broad flattened margin, provided with an exterior narrow rim ; 

 muscular impressions reniform and very deep ; length half an inch ; 

 breadth nearly five-eighths. — B. 



It occurs in abundance in the North Sea, and is found both in a 

 recent and fossil state in Sweden and Norway. — Deshayes. 



12. CRASSINA WITHAMI. N. S— Smith. 

 Plate I. Fig. 24, 25. 



Shell strong, transversely ovate and somewhat depressed ; beaks 

 nearly central and slightly turned to the posterior side, with an ob- 

 long lanceolate impression under them ; external surface, irregular- 

 ly, concentrically wrinkled ; hinge with two strong divergent teeth 

 in the right valve, with a large triangular pit for the reception of the 

 central tooth of the left valve ; inside with two strong, but not large, 

 reniform muscular impressions ; impression of the mantle well marked, 

 and rather deep, which is rendered more decided by a series of ob- 

 long, shallow punctures near its centre ; margin very broad, flat, 

 and plain. 



Found by Henry Witham, Esq. of Lartington, in the marine allu- 

 via at Bridlington Quay on the east coast of Yorkshire. A single 

 valve has recently been dredged at Rothsay Bay, apparently of the 

 same species, by Mr Smith. — B. 



1.3. TELLINA PROXIMA. N. S. — Smith. 

 Plate I. Fig. 21. 



Shell transversely subovate, depressed, thin, with irregular concen- 

 tric strise ; umbo small, placed near the centre, and turning slightly 

 towards the posterior side ; hinge of the right valve provided with a 

 strong tooth next the anterior side, and a very small one on the other 

 side, with a triangular space between them for the reception of the 

 tooth of the opposite valve ; left valve with a rather strong, promi- 

 nent, bifid, central tooth, diverging slightly towards the posterior 

 side, and near to it is situate a single tooth, obliquing slightly in an 

 opposite direction ; length six-eighths of an inch ; breadth an inch. 



When recent this shell has been covered with a pretty strong, 

 fuscous epidermis, as remains of it appear on several of the speci- 

 mens found at Dalmuir. 



The Tellina proximo, is a much stronger shell than the T. tenuis. 

 The teeth are very different, and the fuscous epidermis are charac- 

 ters sufficient to distinguish it at once from that species. — B. 



