WATER SNAILS. 199 
This beautiful mollusk was discovered by Dr. 
Harvey, of botanical renown, in a small Alpine 
lake, and in a stream which flows into it, on 
Cromaglaun Mountain, near the lakes of Kul- 
larney in 1832; not the smallest trace of its 
existence in the many other tarns has been dis- 
covered. It is one of the very few pulmoniferous 
mollusks peculiar to Great Britain, which induced 
the late Professer EH. Forbes to regard it as a 
probable monstrosity of LD. glutinosa. Another 
point of interest regarding this snail, is that the 
shell partakes more of the form of the marine 
Akera bullata than of the other Limneas; but the 
structure of the animal resembles that of other 
species of the genus. Accurate observations, 
however, are required to satisfactorily set at 
rest the disputed point as to whether the present 
species has expanded lobes to the mantle or 
not. 
Dr. W. H. Evans communicated “ An Ascent 
of Cromaglaun Mountain in Quest of Limnca 
involuta,” to the ‘ Naturalist,’ of November, 
1864; from which I extract the following most 
complete account of the natural history of this 
species :— 
“Tts eastern side is almost overhung by the 
perpendicular wall of the higher ridge of the 
mountain, altogether precluding access in that 
quarter; the remainder of the lake being sur- 
