io8 Records of the Indian Museum. [Vol.. XIX^ 



Radular teeth without basal process, either with 



more than three sharp denticulations or with 



three much broader blunt denticulations. 



i. Shell large, heav)', ovoid, with strong spines 

 round the upper extremity of the body- 

 whorl. Operculum without spiral figure, 

 long, narrow, oval... ... ... Melania (^=7'iara). 



ii. Shell as a rule more elongate, without, or 

 with relatively feeble, spines. Operculum 

 bearing a spiral figure. 



a. Shell never very thick or large and as 



a rule relatively long and slender, 

 tapering to a sharp point at the apex, 

 with the aperture ovate and never 

 produced above, the sculpture consist- 

 ing of numerous longitudinal and 

 spiral grooves which form by their 

 intersection a reticulate or nodular 

 pattern, rarely obsolescent. Spines 

 sometimes present on upper extremity 

 of body-whorl. Operculum relatively 

 large, ovate, paucispiral, with the nu- 

 cleus situated near the inner lower 

 margin and the spiral figure occupy- 

 ing only a small part of the surface. 

 Mantle bearing on its inner surface 

 near the margin a row of digitiform 

 processes. Radular teeth relatively 

 long, with numerous sharp denticula- 

 tions ... ... ... Melanoides. 



b. Shell as a rule large heavier and broad- 



er, with more solid sculpture or nearly 

 smooth, more or less biconical in out- 

 line and with the aperture frequently 

 produced slightly both above and be- 

 low. Spines never present on the 

 upper margin of the body- whorl. 

 Operculum relatively small, subcir- 

 cular, with a spiral figure that occu- 

 pies most of its surface. No pro- 

 cesses on or near edge of mantle. 

 Radular teeth relatively short with 

 fewer and blunter denticulations ... Acrostoma. 



Faunus and Mainwaringia do not belong to the freshwater 

 fauna as both are estuarine. The geographical range of the former 

 is wide but in the main insular, while Mainwaringia ' is known only 

 from the Gangetic delta. The synonymy and diagnosis of the two 

 freshwater genera may be discussed further. 



Genus Melanoides, Olivier {nee H. and A. Adams). 



1807. Melanoides, Olivier, Voy. V Emp. Offomau., II, p. 40. 



1854. Plotia, Melania, Tarebia, H. and A. Adams, Gen. Recent Moll., \, 



pp. 295, 301, 304. 

 1874. Melanoides, Melania, s.s. (in part), Plotia, Tarebia, Striatella, Brot. 



Conch. Cab., pp. 6, 7. 

 1885. Melania (s.s), Striatella, Melanella (in part), Tarebia, Plotia, 



Nevill, Hand List Moll. Ind. Mus,, II, pp. 221, 231, 271, 272, 280. 



' Annandale 8r Prashad, Rec. Ind. Mus., XII, p. 251, fig. 5, pi. xx, fig. 8 

 (1919). 



