127 



XXIII. PHYSA. 



Shell reversed, spiral, thin and transparent, oval or 

 oblong : aperture lanceolate or dilated oval, with 

 the peritreme interrupted : umbilicus none : oper- 

 culum none. 



110. PIIYS A. fontinalis. Shell horn-colour, oval, with 

 a very short obtuse spire : aperture dilated at the 

 base. 



Physa fontinalis. Drap. p. 54. t. 3./. 8, 9. 



Brard,p. 167. t. 7./. 7, 8. 



Lamarck) vi. ii. 156. Leach, 150. 



Limnea fontinalis. Sorverby, Gen.f. 8. 

 Bulla fontinalis. Mont. p. 226. 



Linn. Trans, viii. p. 126. t. 4>.f. 1. 



Shell nearly half an inch long, and half as much broad, 

 very thin and fragile : spire extremely short, of 

 four volutions, the lower one much inflated, the 

 others small, and ending obtusely : aperture co- 

 vering nearly the whole of the shell ; pillar slightly 

 sinuate and white, not reflected. 



In rivers and streams, on aquatic plants. 



