LIMNJSA, 57 



like a flint implement of that type, broader and rounded in front, 

 and narrowing behind to a blunt point." — Gwyn Jeffreys. 



Shell oval, thin, fragile, moderately glossy, almost transparent, 

 of a pale amber or horn-colour, with numerous close-set, irregular 

 strice in the line of growth, which are more strongly defined near 

 the suture ; epiderjiiis thin ; whorls 3-4, convex, body whorl 

 occupying by far the greater portion of the shell ; spire sunken, 

 apex slightly raised ; suture distinct but shallow ; mouth large, 

 pear-shaped ; outer lip thin, slightly reflected ; inner lip broadly 

 spread on the penultimate whorl ; fold sharp, narrow. 



Inhabits a small lake on the Cromaglaun Mountain 

 near Killarney. It has not been found in any other 

 locality. 



In the meagre accounts hitherto given of the animal 

 of this singular and beautiful species, the mantle has 

 been erroneously described as covering the exterior of 

 the shell, as in Z. glutinosa. 



Since the publication of his 'British Conchology/ 

 my esteemed friend Dr. Gwyn Jeffreys has had an 

 opportunity of examining living specimens of L. 

 involuta, and has most kindly furnished me with the 

 above accurate description of the animal, from which 

 it will be seen that no part of the exterior of the shell 

 is at any time covered by the mantle ; I have there- 

 fore placed this species in Section B. 



This mollusc may possibly prove to be a form of 

 L, peregra, to which it is, in my opinion, as closely 

 allied as are the varieties lacustris and Biimetti of 

 that species. Its habitat is similar to that of these 

 varieties, and the peculiar form of the three shells is 

 probably owing to the sub-alpine position of the lakes 

 they inhabit. 



This species, according to some writers, occurs in a 

 small stream by which the Cromaglaun Lake is fed, as 



