218 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Galway, South.— SG. 



Lough Derg [C. 0.]. 



Lough Rea [C. 0.]. 

 Kerry, South.— SK. 



Lough Nagarriva (1,200') [J. E. C] [K. & W.]. 



Lough Nalackan (1,150') [K. & W.]. 

 Tipperary, North. — NT. 



Lough Derg [C. O.J. 

 Waterford.— WA. 



Lough Coumshingaun [C. 0.]. 

 HOLOCENE. 

 England. 



Somersetshire, North. — NS. 



Burnham [K. & W,]. 

 Ireland. 

 Down.— DO. 



White Bog, KHlough [C. 0.]. [K. & W.]. 



The initials in [ ] are those of the several collectors who hold 

 specimens, viz. : C. Oldham, J. E. Cooper, H. Overton, and Kennard 

 and Woodward. 



PisiDiUM steenbuchii, MoUer. 



To his paper on " The Pisidium Fauna of the Grand Junction 

 Canal " ^® Mr. Stelfox appended notes on some species which had 

 not been found in those waters. Among these (p. 301) was 

 P. steenbuchii, of which he received for study a single example from 

 Boveney, from Mr. J. E. Cooper, and he suggested that this species 

 is nothing more than a " rather uncommon variety of P. nitidum ". 

 Since then a second specimen has been detected among some other 

 Boveney shells and placed in the same box. 



The original determination of this and other examples from 

 widely different localities was made after careful comparison with 

 co-types of steenbuchii kindly sent me from the Zoological Museum 

 at Copenhagen, but it has seemed well under the circumstances to 

 check this conclusion. Accordingly having been favoured once 

 again by Mr. Cooper with the loan of his specimens, I have com- 

 pared his and my own examples anew with the co-types of steenbuchii, 

 and can find no reason for altering my former determination. 



Of course, looked at carelessly they do superficially resemble 

 nitidmn, save that they are somewhat larger and differ in their 

 sculpturing. The dentition, too, is fairly similar in both species, 

 but there are persistent differences observable by the careful 

 student, which separate them, and the more important of these 

 were duly set forth in the text (to which Mr, Stelfox never seems to 

 refer) of the " Catalogue of the British species of Pisidium ", and 

 need not here be elaborated over again. Mr. Stelfox invites a com- 



" Journ. of Conch., xv, 1918, pp. 289-304. 



