150 LIMN^A PEREGRA. 



markings of a lighter colour, which are readily seen through the 

 shell in the thinner varieties. 



The eyes are at the inner base of the tentacles. 

 In attempting to describe the shell we are confronted with a 

 somewhat difficult task, the variations being so great that it is only 

 by fixing upon a certain form as the type that this can be accom- 

 plished. We, therefore, take the elongated form as our idea of 

 the type, and accept Dr. Jeffreys' description so far as it agrees 

 with our own examination. 



Shell obliquely ovate, thin, 

 moderately glossy, semi-transpa- 

 rent, yellowish-horn colour, irregu- 

 larly striate by the lines of growth, 

 epidermis thin, whorls four to 

 Fig. \.—L. peregra. five, convex, the last occupying 



three-fourths of the shell ; spire produced and pointed, suture 

 rather deep ; mouth large, oval ; outer lip thin (he says), slightly 

 reflected (which scarcely agrees with my experience) ; inner lip 

 folded on the columella, forming behind it a slight umbilical cleft; 

 fold rather prominent and curved. Length three-quarters of an 

 inch ; breadth rather less than half-an-inch. Shell dextral. Dr. 

 Jeffreys mentions some specimens from Ireland, which exceeded 

 an inch and a quarter in length. 



Reeve says there is no fear of mistaking the most widely 

 inflated forms of Limncea peregra for Z. auricularia, but I am not 

 quite sure of this, having personally known instances where this 

 mistake has been made, even in the latest published work on the 

 MoUusca. 



Limncea auricularia has been figured as 

 L. peregra. The long, narrow form — var. 

 elongatissima — has also been mistaken for 

 LirnncBa palustris, and these mistakes made, 



too, by conchologists of ability. For a con- 

 Fig. 2. -var. e^;^ra/^55^wa. ., , , . . , , 



siderable tune it has been customary to 



range Z. peregra next to Z. involuta ; but of late opinion seems to 



be trending in the direction of suppressing the latter form as a 



species, and regarding it as a local variety of an extreme form of 



L. peregra. Even Dr. Gray, who was, as all will admit, a most 



