FAMILY PERISTOMATA. 



191 



Pahidina contecta. 



Genus II. PALUDINA, Lamarck. 



Animal ; oblong, broadly dilated in front, rounded behind, carrying 

 a conically turbinated shell, bead produced into a proboscis, 

 lobed on each side at the base, the right lobe forming the ori- 

 fice to the respiratory cavity, tentacles cylindrical, rising from 

 between the lobes and proboscis, with the eyes raised on a 

 short conjoined stalk. Operculum horny, formed concentric- 

 ally around a sublateral nucleus. 

 Shell ; conically turbinated, of five to six whorls, sometimes umbi- 

 licated, sometimes with the umbilicus nearly closed, aperture 

 moderate, pyriformly rounded, with the lip simple and slightly 

 thinly expanded. 

 The canals, river-inlets, and ponds of Central Europe possess 

 among their numerous small molluscan population already described, 

 two of large size and characteristic structure, called Palu&inm, 

 or Marsh Snails ; and both appear, a little dwarfed in dimensions, 

 in England, more especially in the southern half of our island. 

 They are not found in Scotland or Ireland, although the genus, as 

 we shall presently see, has a much more northerly range, in Asia, 

 even in a more largely developed form. The Paludince constitute 

 an important feature in our English freshwater fauna. They are 

 distinguished by the habit of being ovo-viviparous. The eggs are 



