342 



VIVIPARIDiE. 



Species of Bithynia. 



balthica, Schmidt. 

 bulimoides, Oliv. 

 carinigera, Beck. 

 goniostoma, Nutt. 

 Michaudi, Duval. 

 Orcula, Bens. 

 Preissii, Phil. 



pulchella, Hutton. 

 rubens, Mke. 

 tentaculata, Li7in. 

 thermalis, Linn. 

 ventricosa, Gray. 

 viridis, Poiret. 



Genus NEMATURA, Benson. 



Operculum annular, ovate, thick, shelly, nucleus sub- 

 central, margin grooved. 



Shell oval, compressed ; apex of spire rather acuminate, 

 whorls few, the last large and ventricose ; aperture nearly 

 orbicular, small, oblique, contracted, peritreme conti- 

 nuous, entire. 



Ea^. N. Deltae, Benson, pi. 36, fig. 5. Operculum, N. 

 polita. Cantor, fig. 5, a, 5, b. 



The species of Nematura are inhabitants of India and 

 the Islands of the Eastern Archipelago, and are found 

 either attached to the under surface of floating leaves, or 

 crawling out of the water on the muddy margins of ponds, 

 leaving, as they progress, slender tracks behind them. 



Sjoecies of Nematura. 



coarctata, Lea. 

 Deltae, Bens. 

 glabrata, A. Adams. 

 minima, Bens. 



olivacea, A. Adams. 

 polita, Cantor. 

 puncticulata, A. Adams. 

 ventricosa, Quoy and Gaim. 



