^ 



March, 1908. The Irish Naturalist, 45 



ON LTMN.^A PR.ETENUIS, N.SP., AND L. GLABRA, 



MiJLL. 



BY REV. R. W. B0WEI.1.. 

 [Pr.ATR 2.] ■ 



Through the kindness of Mr. A. S. Kennard I have received 

 original examples from Mr. A. W. Stelfox of the Limnsea 

 found by him and Mr. J. N. Milne in Lough Nagarriva, and 

 figured in his paper entitled " Further Notes on the Land 

 and Freshwater Mollusca of Cork West and Kerr}-," which 

 appeared in the September number of the Irish Natiiratist for 

 1907.1 



Messrs. Stelfox and Milne give in that paper the opinions 

 of some leading conchologists who had examined the shell. 

 All referred it to that curious alpine group which includes 

 L> invot^da and L. Bttrne.tti. I have seen nothing of Biirnetti 

 but the shell, of which I possess a number of old specimens 

 from Loch Skene ; but of involuta Mr. Kennard placed several 

 in my hands for dissection, obtained at Crincaum Lough by 

 the same indefatigable collectors. With these latter came 

 one of the egg-masses mentioned in the paper above referred 

 to ; it contained six embryos, one of which was undeveloped ; 

 the remaining five (alt. about 0.7 mm.) all had intorted spires. 

 I was thus enabled to examine the embryonic radula of L. 

 involuta. 



The peristome of LiynncEa glabra (of which Mr. Kennard 

 has sent me living specimens) is very similar to that of these 

 alpine species. Like them it moves rapidlj^ and exserts the 

 body from the shell. Its radula also presents points of re- 

 semblance ; perhaps the first that strikes one is the regularity 

 of the marginals, which in other Limnseas overlap one another 

 confusedly like strands of bedraggled seaweed. I have there- 

 fore added some notes on this species. One would at first 

 think that glabra must be quite distantl}' related to the 

 species in v.hich the spire is fat or intorted; but the}^ do in 

 fact seem to have ver}- much in common. To put it in a 

 designedly rough and metaphorical way : — Nature seems to 



■• Irish Nat., vol xvi., 1907, p. 2S6. 



