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 Avhich 

 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. 2)ereger were there. The variety under consideration is in- 

 termediate in form between the t}i)ical L. perefier and L. r/lutinosus, 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. pereqer 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. "NVm. 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 diffei's very much in 

 size, according to locality ; mature specimens, Avhich I have found in the 

 cold water of Lough Neagh, where barren of subaquatic plants, did not 

 exceed one inch in length, whereas in di'ains 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 



