Ig20.] N. Annandai^K : Indian Freshwater Gastropods. 109 



1897. Stenomelania, Melanoides, Plofia, Tarebia, von Martens in Weber's 



Zool. Ergebn. Reis. Niederl. Ost-Ind., IV, pp. 40, 50, 62, 69. 



1898. Neomelanien (in part), P. and ¥. Sarasin, Sussix). Moll. Celebes, p. 



1915. Radma, Striafella, Melaiiella (at least in part), Tarebia, Plotia, 



Preston Faun. Brit, hid., Fresliw. Moll., pp. 10, 15, 32, 33, 35. 

 1919 Melavoides, Annandale and Prashad, Rec. Ind. Miis., XVIII, p. 28. 



There has been much confusion in nomenclature owing to the 

 fact that H. and A. Adams used the name Melanoides in quite a 

 different sense from that in which it had been introduced thirty- 

 seven years earlier by Olivier, who applied it to a race or phase of 

 the common " Melania" tuherculata. A reference to this author's 

 ''voyage" shows that Nevill {op. cit., p. 248) was wrong in stat- 

 ing that the form of the name employed was " Melanoide," a form 

 that might not have been considered valid, and Preston has ig- 

 nored von Marten's remarks on the subject. 



M. tuherculatus (Miiller), the type of this genus, is perhaps 

 the most widely distributed of all the non-marine Gastropods that 

 occur in India, for it is found in most parts of the Oriental and 

 Ethiopian regions and even in parts of the Palaearctic and Aus- 

 tralasian Regions adjacent to them. With this species a large 

 number of Oriental forms must be associated generically on 

 account of the fact that they possess the characters noted in the 

 key. The Sarasins were the first authors to lay stress on the peculi- 

 arities of the radulae and opercula of these forms, but they were 

 apparently not acquainted with the peculiarities of the mantle. 

 They did not regard the structures the}^ examined as of generic 

 importance and associated species I retain in Melania with those 

 here assigned to Melanoides in their group ''Neomelanien." 



The description given in the key, with the figures published 

 in the various works to which I have referred, should render the 

 recognition of species of the genus easy, if the animal as well as 

 the shell be examined. The processes of the mantle are arranged 

 in a small series along a line running parallel to the margin. As a 

 rule they increase in size from left to right. When the animal is 

 fully expanded they are elongate and pointed and often resemble 

 small parasitic leeches protruding from the mouth of the shell. 

 In preserved specimens they are as a rule contracted and much 

 less conspicuous. 



Genus Acrostoma, Brot. 



1854. Melanoides, H. and A. Adams {nee Olivier), Gen. Recent Moll., I, 



p. 296. 



1874, Melanoides, Acrostoma, Brot, op. cit., p. 7. 



1885. Melanoides, Acrostoma, Nevill, op. cit., pp. 248, 270. 



1897. Brotia, von Martens, op. cit., p. 33. 



1898. Palaeomelanien, P. and F. Sarasin, op. cit., p. 30. 

 1915. Melanoides, Acrostoma, Preston, op. cit., pp. 21, 30. 



I cannot find r ifi:erence of generic ir;.^o!ta-.iCe beUve^n 



the soft parts, rad;-^^ , operculum or shell of Br aria, von Mf^ ce:i? 



{ = .\l la- oides, ■ .1 and Acrostoma, Br-jt. Indeed, in the single 



species i cad ,cr stoma variabile (Benson) an almost complete 



