164 



[Proc. B.N.F.C., 



in West Donegal, Tempo, in Fermanagh, and on Achill Island, in 

 West Mayo. It should, however, occur in the Ox Mountains, 

 in Sligo and East Mayo. 



Limnaea auricularia (L.). A young specimen of the var. 

 acuta Jeffreys, was taken in Lough Gill, in Sligo, in July, 1904, 

 but until recently passed unnoticed among examples of L. pereger, 

 collected on the same occasion near Doonee Rock. 



Planorbis glaber Jeffreys. A single specimen of this local 

 shell was taken in Trawane Bay, Lough Gill, Sligo, in April, 1914. 



The records given in the former list {Joe. cit.) for Succinea 

 putris are all erroneous, and should be referred to S. pfeifferi. 

 Succinea putris, however, does occur in the district, and was taken 

 in April, 19 14, in the great meadow at the head of Trawane Bay, 

 on the Sligo side of the boundary between that county and 

 Leitrim. Likewise, the records for the various Pisidia must be 

 withdrawn for the present, owing to Mr. B. B. Woodward's 

 revision of this difficult genus. 



Freshwater Mollusca. — The district under consideration 

 having been heavily glaciated during the Pleistocene period, it 

 may be taken that the freshwater Mollusca now found here must 

 have migrated into this region in post-Glacial times. It seems 

 probable that the route by which the bulk of the species found 

 their way was, via Belhavel Lough, from the Shannon basin to the 

 south-east. Lough Erne has possibly received its fauna in a 

 similar way from the Shannon, but across the low-lying ground 

 about Lough Garadice. It is interesting, therefore, to compare 

 the respective molluscan faunas of Loughs Erne and Gill, and to 

 contrast these with that of the basin in which lies Lough Melvin, 

 which has not the same proximity to the Shannon drainage area. 

 The little basin of Glencar lies between Loughs Gill and Melvin, 

 but as they are not separated by any considerable barrier, its fauna 

 closely resembles that of the former lake. The following table 

 shows the various species found in these four basins, for which I 

 can find authentic records : — 



