142 MARSHALL : ON HYDROBI^ AND ASSIMINE^E. 



habitat, which was correct twenty years ago, has undergone 

 some change in the interval. At that time Clark and Barlee 

 found it in myriads between Greenwich and Charlton, but at 

 the present time neither Mr. Jeffreys nor myself can find it 

 there. We have, however, found it in countless thousands at 

 AbV)ey Wood and Erith, on the raised banks of the Thames, 

 which now seems its nearest locality to London, so that they 

 appear to have migrated for a distance of about ten miles." As 

 Mr. Hbrsley has been searching for this species also at the 

 latter stations without success, it must have migrated further 

 still, if the Sewage Outfall Works of recent years has not alto- 

 gether exterminated it. 

 Sevenoaks, Torquay. 



NOTES ON BRITISH HYDROBIJE WITH A 

 DESCRIPTION OF A SUPPOSED NEW SPECIES. 



By EDGAR A. SMITH, F.Z.S. 



A few weeks ago Mr. A. J. Jenkins submitted to me for 

 determination some specimens of Hydrobia which he had 

 collected at Plumstead and which he was unable to identify 

 satisfactorily with any of the British species as they are usually 

 understood by English conchologists and as described and 

 figured by Jeffreys in his ' British Conchology.' At the com- 

 mencement of 1889 similar specimens were sent me by Mr. W. 

 Crouch who found them inhabiting ditches at Beeton near 

 North Woolwich. 



After careful consideration I have arrived at the conclusion 

 that they must belong to a distinct species for which I propose 

 the name H. jenkinsi. In order to ascertain if it was known as 

 a continental species * I sent specimens to Dr. Boettger, of 



* It is quite impossible to identify these small species from description 

 and figures. Between two and three hundred forms from Europe alone 

 under the various names of Hydrobia, Paludinella, Atunicola, Bythinella, 

 Peringia, Belgiandia, &c., &c., have already been described. 



J.C, vi., Oct., i88g. 



