I92I.] 



Manipur Molluscs. 



573 



Shells from Diiuapur, Assam, are a little smaller, narrower and 

 less symmetrical than those from Manipur. 



Measurements nf Shells (in millimetres). 



Length . . 

 Breadth 



'Length of aperture . . 

 Breadth of aperture 

 Length of spire (dorsal view) 

 Breadth of spire (dorsal view) . 



All the above specimens are from a swamp at Thanga Island 

 in the Loktak Lake. 



Fig. 13.— Radular teeth of Limnaea. 



A. L. ovalior, Annandale and Prashad. 



B. L. andersoniana, Nevill. 



The animal is of unusually dark colour with the mantle black, 

 unspotted or with faint and relatively small round spots, and 

 with pale margin. As in all Indian species examined by us, the 

 tentacles seem to be shorter than those of some European forms. 

 The cephalic lobes are large and broad and the foot is compara- 

 tively small, bluntly pointed behind and somewhat expanded at 

 the antero-lateral angles The eyes are small. 



The mouth is small and the upper jaw stout, semicircular and 

 black. The lateral pieces are slender but well cornified and dark 

 in colour. The radula is short and broad, narrowing abruptly in 

 front and rounded at the tip. The whole buccal mass is relatively 

 small. The dental formula is approximately 19.12.1.12 19. The 

 lateral and marginal teeth are well differentiated and the latter 

 have a deep yellowish tinge. The cusp of the central is stout and 

 relatively large, with a distinct lobe on the right side. The later- 

 als are distinctly tricuspid, but the entocone is much shorter than 

 the other cusps and is apt to be concealed by being turned in 

 under the mesocone. The mesocone and ectocone are long and 

 sharp. The laterals are unusually stout. They are multicuspid 



