404 JOURNAL OF CONCHOLOGY. 



Stream the River Taas at Stoke Holy Cross (S.S.P.) ; in 

 ditches at Cohiey, Thorpe, and Old Lakenham (A.M.). 



P. fontinale (Drap.). Common. Ditches at Stoke Holy 

 Cross, Surlingham Ferry, near Horning Ferry, shallow part 

 of Ran worth Broad (S.S.P.) ; Thorpe, Old I^akenham, 

 Swainsthorpe, Costessey (A.M.). 



. Var. pulchella Jenyns. Ditch at Colney (A.M.) ; with type 

 at Stoke Holy Cross (S.S.P.). 



P. pusillum (Gmelin). Shallow water. Hickling Broad 

 (S.S.P.) ; in a ditch in wood at Costessey, Old Lakenham 

 . (A.M.). 



P. milium Held. Sparingly in a ditch at Old Lakenham 

 (A.M.). 



All the above species, except those enclosed in brackets, 

 have been submitted to the inspection of Mr. Taylor and Mr. 

 Roebuck, of the Conchological Society, and we have to thank 

 them for undertaking to look them through and making several 

 suggestions. Two species recorded by Mr. Bridgman have 

 eluded our notice so far, namely, Aciada li/ieata, two specimens 

 of which were recorded from Caistor Woods ; and CcBcilioides 

 acicida MiilL, which I am rather surprised at not having taken 

 dead or alive. 



Dreissensia polymorpha Pallas. — Would you allow 

 me to ask of any of your readers whether the proper name of 

 this species should not be D. volgensis7 Pallas's name was 

 published before 1758, the starting-point of our nomenclature, 

 and included both a marine and freshwater form. Either of 

 the above two reasons seem sufficient to invalidate the use of 

 the name. — A. A. 



J.C., vii., July 1894. 



