BYTHINIA. 61 



adult specimens ; their place being supplied by a nearly flat 

 and semispiral plate, as in Bulimus decollatus. 



Var 3. excavata. Whorls more rounded, and suture much 

 deeper. 



HABITAT : Slow rivers, ponds, and still waters every- 

 where in England, Wales, and Ireland, as well as at 

 Frazerburg in Aberdetashire ; and it is perhaps the 

 most abundant fossil in the lacustrine beds of our upper 

 tertiaries. Var. 1. Devonshire (Mus. Turton) ; Bristol 

 and Wandsworth ( J. G. J.); Richmond, Surrey (Choules). 

 Var. 2. Woolwich and Cardiff (J. G. J.); Co. Armagh 

 (Waller). Var. 3. Cardiff (J. G. J.). This last variety 

 seems to connect the present species with B. Leachii', but 

 it differs from the last-mentioned species in its greater 

 size, as well as the oval shape of the mouth. B. tenta- 

 culata ranges from Siberia to Sicily. The animal is 

 sluggish, but irritable. It sometimes floats, or creeps 

 on the under surface of the water. Draparnaud says 

 that it feeds on animal as well as vegetable substances. 

 The shell is often encrusted with a ferruginous or mineral 

 deposit. From this circumstance Draparnaud derived 

 the name of impura which he gave this species, having 

 needlessly changed the prior one assigned to it by Linne*. 

 The epidermis in young specimens is slightly hispid and 

 resembles a fine velvety pile. 



This species was first made known and admirably 

 described by our countryman, Lister. 



2. B. LEACH'II*, Sheppard. 



Turbo Leachii, Shepp. in Linn. Trans, xiv. p. 152. Bithinia Leachii, 

 F. & H. iii. p. 16, pi. Ixxi. f. 7, 8, and (animal) pi. H. H. f. 4. 



BODY greyish -white, with black and yellow specks : ten- 

 tacles very flexible : foot slender. 



* Named after Dr, Leach, a celebrated English zoologist, 



