PALUDINA. 57 



Shell conical, moderately solid and glossy, yellowish, with 

 sometimes a green or brown tinge ; the last whorl ha^dng 3, 

 and each of the two preceding whorls 2, spiral brown bands, 

 the uppermost of which is usually the broadest ; there are also 

 numerous and very fine spiral striae, besides faint and irregular 

 lines of growth : epidermis rather thick : wliorh 7, extremely 

 convex ; the last being . equal to about one-half of the shell ; 

 they increase gradually in size, except the two first, which 

 are disproportionately small and twisted, resembling those of 

 Succinea : suture remarkably deep : mouth oval, or approaching 

 to a circular shape : outer lip sharp and slightly reflected : iymer 

 lip separate from the columella ; both lips forming a complete 

 peristome : umbilicus small, oblique, but very distinct and deep, 

 exposing part of the internal spire : operculum rather thin, 

 compressed towards the nucleus, which causes the under side 

 to project, like the boss of a shield ; it is marked with nume- 

 rous concentric striae and more distant lines of growth. L. 1-5. 

 B. 1-25. 



Habitat : Slow rivers^ canals^ and large pieces of 

 standing water^ thronghout the greater part of England, 

 as far north as Yorkshire. It is, however, rather local. 

 This is a Finland species, and ranges south to the 

 Pyrenees. 



This moUusk, when at rest, adheres firmly to stones 

 and wood ; but on being touched, it immediatelly falls oil". 

 It sometimes attains to a large size, one of my specimens 

 being more than 2 inches long and If broad. 



The Linnean description of Helix vivipara accords 

 more properly with that of the next species, which has 

 only an umbilical chink (^^mperforata^^), and is pecu- 

 liarly '^'^ subovata^^ and "obtusa.^^ The name given by 

 Millet to the present species, which does not appear to 

 have been known to the authors of the ' British Mollusca,^ 

 must of course be adopted in preference to the very 

 modern one of '' Listen'^ which was proposed by them. 

 Miiller considered this species to be that of Linne ; and 

 he described the other as Nerita fasciata. 



d5 



