VOLUME XVII. 



BYTHINIA LKACHII, 



AN ADDITION TO THE IRISH FAUNA, 

 WITH SOME NOTES ON ITS DISTRIBUTION AND ALSO ON 



THAT OF PLANORBIS CORNEUS. 



BY R. WELCH, M.R.I.A. 

 (PI.ATE I.) 



In searching a canal or river for freshwater shells one may 

 sometimes come across a 3'oung specimen of that widely dis- 

 tributed species Bythinia te7itaciilata with a deeper suture and 

 more slender form than usual. This is especially the case in 

 dead eroded specimens, and when R. LI- Praeger and T found 

 what I thought at first was Dythiiiia Lcachii in the Mountmel- 

 lick branch of the Grand Canal near Monasterevan, in 1899, 

 I came to the conclusion finall}^ that thej- were only a slender 

 local form of the commoner species with a deeper suture than 

 usual (like D., fig. i). With A. W. Stelfox as an addition to 

 our part}', we visited the same locality again in September, 

 1906, and for the same reason, to collect Plariorbis cor^ieiis in 

 the shallow drains of the district, the centre of its distribution — 

 and that a very restricted one — in Ireland. Before starting on 

 our walk across countr}^ however, we visited both the River 

 Barrow and the canal, and in the latter, in the old locality 

 north of the railwa}^ we obtained a lot more Bythinia. These 

 A. W. Stelfox took home with him, and on comparing them 

 carefully with specimens of ^. Leachii that he had collected in 

 England, came to the conclusion that they were clearly that 

 species. They were, however, almost all immature specimens, 

 so we sent them to our friends R. Standen and J. W. Jackson 

 to be compared with various local sets in the Conchological 



