STRI.FOX : ON 'I'lIE MISAm.ICATION OF PISIDIUM NAMKS. 239 



in his Catalogue, pi. i, fig. 9, certainly resembles forms of P. caser- 

 tanion as stated in the text, p. 46 ; but the majority of the shells 

 named F. nitidiim by Mr. Woodward which have passed through my 

 hands — mainly from the collections of Messrs. J. E. Cooper and R. A. 

 Phillips — do not bear any great resemblance to the above mentioned 

 figure, and in my opinion are referable to normal forms oi P. obtusale. 

 Whether, under the circumstances, Jenyns's name P. pusillum must 

 replace that oi P. personatum is more a matter for those who interest 

 themselves in questions of nomenclature than for a field naturalist ; 

 but as the name P. pusillum of pre-Jenyns authors appears to have 

 covered all the smaller species of the genus indiscriminately, and as 

 it is admittedly impossible to say what the original P. pusillum of 

 Gmelin really was, I would suggest that, to avoid future confusion, 

 the name should be dropped. 



The three species involved, therefore, would be named as follows :- 

 P. personatum Malm (fide B. B. Woodward) 



= P. pusilhan Jenyns. 

 P. casertanum (Poli) B. B. Woodward 



= P. pusillum Jenyns, in part. 

 P. nitidum Jenyns 



= P. pusillum B. B. Woodward. 



The evidence adduced by Mr. Woodward in support of Poll's name 

 casertamim is not very convincing, but as it tends to confirm the 

 tradition held by many French authors, I think that it would be best 

 to accept it rather than to turn to the P. australe of Philippii, which 

 just antedates Alder's name cijiereum. 



The casual reference to P. hibernicum in Mr. Oldham's notes may 

 come as a surprise to many, and it may be well to explain that we 

 now know this species to be widely distributed in the British Islands, 

 though hitherto confounded with P. obhtsale and P. nitidum {P. pti- 

 silltn?i, B. B. Woodward). It may be found in association with these 

 species in many localities that we know of, and there is therefore no 

 doubt that it is distinct from both. That it has so long escaped 

 notice is no doubt due in part to the fact that since the time of Jeffreys 

 no ecological work seems to have been attempted in this group. The 

 unfortunate fact that Westerlund described the species from the very 

 aberrant form that lives in the semi-alpine Lough Nagarriva, has per- 

 haps caused conchologists to overlook it, though once known it is one 

 of the easiest species to recognise, even in the field. 



For their kind co-operation in the preparation of these notes, I wish 

 to tender my thanks to Messrs. Charles Oldham and R. A. Phillips, 

 and especially to the former for English and Welsh material and for 

 his notes on the Jenyns types. My thanks are also due to Mr. J. E. 

 Cooper for permitting Mr. Phillips and myself to examine a large 

 series of shells named P. 7iitidum and P, pusillum by Mr. Woodward. 



