Stelfox — List of Land and Freshwater Mollusks of Ireland. 119 



Lough Neagh basin, though first ob- 

 served there in 1898. From its pre- 



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sence in lakes on the Aran Islands, on 

 the Dingle peninsula, and in other 

 isolated stations along the -west coast, 

 it can scarcely have been introduced 

 with timber, as was originally sug- 

 gested ; and it is, I think, certainly 

 native. But that it has recently spread 

 locally I also firmly believe ; for in its 

 present abundance it could not have 

 been long overlooked. 



The testimony of Mr. J. N. Milne 

 would alone convince me of this fact, 

 and there is also that of other con- 

 chologists to confirm his statements. 

 Mr. Milne's experience is briefiy as 

 follows : he collected regularly for 

 many years, in the marshes opposite 

 Culmore and at Limavady in Derry, and 

 in those of Inch in East Donegal, the 

 dominating species always being Plan- 

 orhis crista, P. spirorbis, and Aplecta 

 hypnorum. After the lapse of but a few 

 years, he again visited these localities 

 during the closing years of the last 

 century, and found that Paludestrinajen- 

 kinsi had appeared in enormous numbers, 

 and was undoubtedly the dominant 

 species. At Inch he failed to find any 

 specimens of Planorhis crista, though 



the other two shells were still there. 

 During the month of June, 1909, I had 

 an opportunity of working Mr. Milne's 

 station at Limavady Junction. No ex- 

 amples of Planorhis crista were seen ; but 

 one of P. spirorhis and several of A. 

 hypnorum were taken, while every scoop 

 brought up hundreds of P. jenkinsi. 

 After the first frosts of autumn, millions 

 of dead shells of this species may be 

 collected along the shores of Lough 

 Foyle, and on those of Lough Neagh, 

 thrown up by waves in large wreaths, 

 which sometimes measure several feet 

 long and may be inches in depth. Like 

 all adaptable species, it shows great local 

 variation, each stationhaving some diffe- 

 rent characteristics ; but the prevailing 

 form is smooth, the vars. carinata and 

 coronata being more local, though in 

 certain localities these may predomi- 

 nate. 



Paludestrina stagnalis (Baster). 



TurhoUhae, Brown, Mem. Werner. Soc, 

 vol. ii, p. 521, 1818. Mydrohia 

 ulvae, Scharff, Irish Naturalist, 

 p. 178, 1892. 



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Common in rnost estuaries, and occurs 



