LIMN^A. 103 



or less intorted^ resembliug in this respect tlie form of 

 L. involuta. Tiie present species ranges from Finland, 

 througli Sweden, Germany, and France, as far south as 

 the Pyrenees. 



It is rather an active mollusk, and nearly always in 

 motion. Bouchard-Chantereaux.says that each of its 

 capsules contains from 30 to 40 eggs. In the young the 

 shell is entirely covered by the pallial fold. 



2. L. involu'ta*, Thompson. 



Limnetis invohctus, (Harvey) Thomps. in Ann. Nat. Hist. v. p. 22. Lim-. 

 TUBUS involutus, F. & H. iv. p. 184, pi. cxxii. f. 11. 



Body unknown as to its external parts, except that the 

 greater part of the shell is covered by the mantle. 



Shell oval, rather glossy, semitransparent, yellowish -horn- 

 colour with a tinge of brown, closely but irregularly striate by 

 the lines of growth, which are stronger towards the suture, 

 often impressed and sometimes constricted by a few spiral 

 grooves in different parts of the shell : ejndermis thin : luhorls 

 3-4, convex, the last covering all the rest except the point of 

 the spire or nucleus : spire flat or slightly concave, with the 

 point upraised and twisted : suture distinct, but not deep : 

 nioutJi pear-shaped : oiiter li}:) thin, slightly reflected : inner Vp 

 much spread on the columella : fold narrow and sharp. L. 0*4. 

 B. 0-275. 



Habitat : A small mountain-lake, and a stream which 

 flows into it, at Cromaglaun near Killarney ; not rare. 

 In one of my specimens, which has the mouth some- 

 what contracted below, a tendency to an umbilical cleft 

 is observable. 



It is strange that no other locality but the one above 

 mentioned has ever been discovered, here or abroad, for 

 this remarkable species. It has some affinity to L. glu- 

 tinosa, and may ultimately prove to be an aberrant form 

 of that species, corresponding with the variety Burnetti 



* Having the spire intorted or sunk. 



