LIMN^A. 109 



4-5, very much swollen and expanded in front, the last occu- 

 pjing at least five-sixths of the shell : spire oblique, exceed- 

 ingly small, but produced and ending in a sharp point : suture 

 very deep : mouth extremely large, roundish oval, a little con- 

 tracted and nearly truncate on the inner side both by the 

 penultimate whorl and the columellar fold : outer lip thin, con- 

 siderably reflected : inner lip slightly thickened on the colu- 

 mella and forming behind it a slight umbilical cleft : fold 

 prominent, strongly curved and sharp. L. 1-125. B. 0*825. 



Yar. 1. acuta. Body of a greyish colour and closely covered 

 with black spots. Shell smaller than the tj^ical form, more 

 oblong, and having the last whorl and mouth proportionably 

 narrower. Limneus acutus, Jeffr. in Linn. Tr. xvi. p. 373. Lim- 

 nceus auricularius, var., F. & H. iv. p. 171, pi. cxxiii. f. 2. 



Var. 2. albida. Shell smaller and thinner, white, with a 

 shorter spire and less distinct strias. L. 0-675. B. 0-55. 



Habitat : Lakes, marshes, slow rivers, canals, deep 

 ditches and large ponds in most parts of Great Britain ; 

 but it is local, and does not satisfactorily appear to have 

 been found in Scotland. Var. 1. Marshes on the sea- 

 coast of Glamorganshire; Church Stretton, Salop; Kent; 

 Co. Tyrone (J. G. J.) : Yoxford, Suffolk (Barlee). This 

 variety is intermediate betw^een L. peregra and the pre- 

 sent species ; but being found only with the former spe- 

 cies, I am inclined to think it belongs to L. auricularia. 

 A monstrosity of this form in my collection has a second 

 or inner mouth formed by a plate on the columellar 

 side. Var. 2. Bath (Clark); Blenheim lake (Mrs. Richard 

 Smith). The variety acuta is one of our upper tertiary 

 fossils. This species ranges from Siberia to Portugal. 



Its habits are inactive ; and when it crawls, only the 

 front edge of its mantle and the tentacles are perceptible. 

 It occasionally may be seen floating on the surface of 

 the water. It is apt to be infested, as well as its con- 

 geners, by an annelid allied to the Nais vermicularis of 

 Miiller, which usually takes up its abode between the 



