PALUDINA. 57 



SHELL conical, moderately solid and glossy, yellowish, with 

 sometimes a green or brown tinge ; the last whorl having 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 Bather thick : whorls 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 : inner 

 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, throughout 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 mollusk, when at rest, adheres firmly to stones 

 and wood ; but on being touched, it immediately falls off. 

 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 (" imperforata "), 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 " Listeri " which was proposed by them. 

 Miiller considered this species to be that of Linne* ; and 

 he described the other as Nerita fasciata. 



