55t 



Records of the Indian Museum. 



[Vol. XXII, 



of the genus have been revised, it seems best to regard it provi- 

 sionally as a species. I figure the radular teeth. 



In Manipur P. matira was found (in February and March) 

 buried in the mud at the edge of certain ponds in or near Imphal, 

 the capital. Dead shells were also found round these ponds, but 

 not elsewhere in the vallev. In the garden of the Residency the 

 species was fairly abundant in one of two ponds, but not in the 

 other. Both were shallow and had a dense submerged vegetation 



Fig. 8. — Radular teeth of Pachylabra minim- 



of Potamogdon and Hydrilla, with a not very dense floating vege- 

 tation of Azolla, etc. The only difference seemed to be that in 

 the pond in which Pachylabra occurred lotuses had been planted, 

 and that there were none of these plants in the other. The other 

 ponds in which the mollusc was found had a still richer submerged 

 and floating vegetation with a profuse growth of plants that sent 

 out long runners on the top ot the water. Most species of the 

 genus are dependent for their food on succulent leaves and stems 

 and prefer such vegetation to the ordinary submerged water-weeds. 



Family MELANIIDAE. 



Subfamily MELANIN AE. 



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



1807. Melanoides, Olivier, Voyage I'Emp. Ottoman II, p. 40. 



1854. Plotia. Tarebia, H. and A. -Adams, Gen. Recent Moll., pp. 



295. 304- 

 1874. Plotia, Tarebia, Striatella, Brol, Conch. Cab., p. 7. 



1897. Stenomelania, Tarebia, Melanoides, Plotia, von Martens, in 



\\'eber's Zool. Ergebn. Niederi. Ost. Ind. IV. pp. 40, 50, 62, 69. 



1898. Neomelanien (in part), P. and P". Sarasin. Siissiv. Moll. Celebes, 



p. 38. 

 1915. Radi)ia, Striatella, Melanella (in pari), Tarebia, Plotia, Preston, 

 Faun. Brit. Ind., Fresliw.-Moll , pp 10, 15, 32, 33, 35. 



1919. Melanoides, Annandaleand Prashad, Rec.Ind. Miis. XVIII, p. 28. 



1920. Melanoides, .'Knnandale, ibid-, XIX, p. 108. 



In the paper by Dr. Baini Prashad and myself cited imme- 

 diately above we have given reasons for uniting Melanoides, s.s. and 

 Plotia. Our views on this point are further strengthened by an 

 examination of a large collection from various parts of the Madras 



