62 PALUDINID^. 



SHELL conical, rather thin, glossy, and semitransparent, 

 greyish horn-colour or amber, microscopically striate in a 

 spiral direction, and irregularly marked by the lines of growth : 

 epidermis extremely thin : whorls 5, very con vex and rounded, 

 but narrow, the last occupying about one-half of the shell : 

 spire rather abruptly pointed : suture nearly straight, ex- 

 tremely deep : mouth nearly round, very slightly angular above, 

 where the outer lip meets the columella: outer lip rather thick, 

 and strengthened by a slight internal rib, scarcely reflected, 

 except below : inner lip forming with the other lip a com- 

 plete peristome : umbilicus small and narrow, but distinct : 

 operculum almost circular and flat, otherwise like that of the 

 last species. L. 0'25. B. 0-2. 



Var. elongata. Shell smaller ; spire more produced. 



HABITAT : Nearly the same as that of B. tentaculata ; 

 but the present species does not extend so far north, 

 and it is more local and much less abundant. It is 

 also equally rare as a tertiary fossil. The variety is 

 from Woolwich marshes and Northampton. Malm has 

 recorded this species as Swedish ; and Morelet has 

 noticed it as inhabiting Algeria. 



This species is distinguishable from the last, in com- 

 pany with which it is sometimes found living, by its 

 much smaller size, the whorls being more swollen and 

 narrower (giving the shell a scalariform appearance), the 

 very deep suture and distinct umbilicus, as well as by 

 the shape of the mouth and operculum. It is sometimes 

 known by the specific name of ventricosa, which was origi- 

 nally given to it by Dr. Gray, but without any description. 

 The Cyclostoma simile of Draparnaud, to which the pre- 

 sent species has been referred by some authors, is very 

 different, as will be seen presently. Specimens in Dr. 

 Turton's collection, named respectively " Paludina simi- 

 lis" " P. viridis" and " P. anatina," all belong to B. 

 Leachii, being merely different stages of growth. The 

 late M. D'Orbigny gave me, at Rochelle, in 1830 some 



