304 
MOLLUSCA. 
Cumberland — their donor General Bingham. It would seem to be the 
same form which Capt. Brown figures under the name of “ Lymnsea la- 
custris, Brown’s MSS.,” and states to have been found by him in Loch 
Leven, Kinross-shire. Illustrations Brit. Conch., pi. 42, f. 24, 25. From 
lakes in various parts of Ireland I possess this form, which, from its ex- 
treme delicacy, I look upon as an inhabitant of still water, and from its 
rare occurrence, except when cast ashore, of deep water also. The spe- 
cimens which, containing the living animal, have occasionally been found 
in shallow water have, I presume, been driven thither in storms, to which 
conclusion I am led by having once at Lough Erne, and frequently at 
Lough Neagh, looked in vain for a living individual with a shell of this 
form at the edge of their waters, though plenty of the more common 
forms of L. pereger were there. The variety under consideration is in- 
termediate in form between the typical L. pereger and L. glutinosus, with 
a short spire and ample aperture ; shell very thin, longitudinally striated ; 
striae regular, frequent, and strongly marked ; about one in thirty of the 
specimens examined, somewhat spirally cut, “ like the facets of glass ; ” 
slight fold on the pillar lip ; an epidermis-like covering, of a dull green- 
ish-yellow colour. By the chief cultivators of this branch of natural his- 
tory in Great Britain, to whom I have sent this shell, it was considered a 
particularly well-marked variety, and M. Michaud, in acknowledging the 
receipt of specimens from Lough Neagh, remarked that the form was un- 
known to him in France. 
I have seen the L. pereger attached in numbers to the backs of turtles, 
kept in a pond at Fort William, near Belfast, when it was amusing to 
observe these animals swimming about, with the Limnei still keeping 
“ their seats ” upon them. Tory Island, Mr. Hyndman, August, 1845. 
L. involutus, Harvey. 
This Limnens so remarkable in form was discovered by Dr. Wm. H. 
Harvey, in a small lake on Crommaglaun Mountain, near the lakes of 
Killarney. A description of it will be found in the Annals Nat. Hist, for 
March, 1840, p. 22. Its specific character is — spire sunk within the outer 
whorl ; aperture very large, extending to the apex. 
L. stagnalis, Drap. 
This, the largest European Limneus, though by no means generally 
distributed, occurs in every portion of the island. It differs very much in 
size, according to locality ; mature specimens, which I have found in the 
cold water of Lough Neagh, where barren of subaquatic plants, did not 
exceed one inch in length, whereas in drains in which such plants abound 
they attain double this size. 
A Limneus collected by my friend Richard Langtry, Esq., of Fort 
William, near Belfast, when on a tour through Upper Canada in 1835, 
seems identical with L. stagnalis. It differs from the ordinary form only 
in tapering rather more towards the apex, and in the second largest 
volution being a little more tumid ; but in these respects an extensive 
series of Irish specimens before me differ very much. The American 
specimens were taken in the river connecting Buckhorn with Pigeon 
Lake. 
L. palustris, Drap. 
Common, and generally distributed over Ireland — in size, form, and 
colour very variable. In the river Bann, near Kilrea, I have procured 
