190 



few, the last large and ventricose ; aperture nearly orbicular, 

 small, oblique, contracted ; lip continuous, entire. 



Nematura is a genus of small freshwater shells, of which the animal has 

 not been described, inhabiting the margins of ponds in India and in the 

 islands of the Eastern Archipelago. They attach themselves mostly to the 

 under surface of floating leaves. The shell has an unusually small aper- 

 ture, of which the margin is continuous. 



1. coarctata, Lea. 



2. Delta?, Bens. 



3. glabrata, Adams. 



Species. 



4. minima, Bens. 



5. olivacea, Adams. 



6. polita, Cantor. 



7. puncticulata, Ad. 



8. ventricosa, Quoy. 



Nematuea Delt,e. 

 aperture. 



Figure. 

 PI. 20. Fig. 1 08. Shell, showing its small rounded 



Genus ASSIMINEA, Leach. 



Animal ; with short obtuse tentacles, the eyes being placed near 



their ends. 

 Shell ; ovately conical, with the spire more or less produced ; whorls 



convex, scarcely umbilicated ; aperture ovate ; lip simple. 



A small amphibious mollask, inhabiting brackish water on the Kentish 

 shores of the Thames, a little resembling Pahidina. The genus is also 

 found in India, China, Australia, and the Pacific Isles. 



Species. 



1. Francesia, Benson. 2. Gravana, Leach. 



Figure. 



Assiminea Oparensis. PI. 18. Fig. 96. Shell, of a new species from 

 the Island of Opara, showing its Paludina-Wke, form. 



