FAMILY PERISTOMATA. 



195 



An attentive comparison of the shells of this and the following 

 species, will show that they are distinguished from each other by- 

 well-marked differences. Paludina contecta has a larger shell than 

 P. vivipara, composed of a whorl more. The whorls are tumidly- 

 produced, obtusely angled round the upper part, which gives them 

 a somewhat narrow appearance, and being coiled around a broader 

 axis, a deep umbilicus is left in the centre. The colour is a dark 

 olive-green, with the bands darker still, and more defined. The 

 animal of P. contecta is a dingy brown, crowded with minutely 

 speckled yellow dots. 



The range of both species of Paludina is curiously confined in 

 Britain to England. One or two stray dead shells of the genus 

 have been found in Scotland, but there is no record of the animal 

 having been taken alive ; nor has it been taken alive in Ireland. 

 The northern limit of Paludina in Britain, is in Yorkshire and 

 Lancashire. On the Continent, Paludina contecta and vivipara 

 range as far north as Finland. Their chief area of habitation is in 

 Central Europe, extending, more scattered, to the Mediterranean. 

 It has been stated that P. contecta is not found south of the Pyre- 

 nees, but we have little doubt that M. Charpentier's P. ampullacea, 

 a native of Italy, is a variety of it. 



2. Paludina vivipara. Viviparous Paludina. 



Shell ; obtusely ovately turbinated, minutely compressly uinbili- 

 cated, rather stout, fulvous olive, encircled with three purple- 

 red bands, whorls four to five, longitudinally densely pHcately 

 striated, moderately ventricose ; aperture somewhat pyriformly 

 rounded, lip simple, a Httle expanded. 



Helix vivipara, Linnseus (1758), Syst. Nat. ed. 10. p. 772. 



Nerita fasciata, Miiller (1744), Verm. Hist, part ii. p. 182. 



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