XV. MATERIALS FOR A GENERIC REVISION 

 OF THE FRESHWATER GASTROPOD 

 MOLLUSCS OF THE INDIAN EMPIRE. 



Introductory Note. 



[Under the above title I propose, with the help of other members of the Zoo- 

 logical Survey of India, to issue a series of short papers embodying the main taxo- 

 nomic results of our recent survey of the freshwater molluscs of India.' The defini- 

 tions and limitations of the genera we have adopted are in many instances 

 different from those hitherto accepted, and it will be as well that our views should 

 be subjected to criticism, which we will welcome, before our final monograph is 

 published. N.A.']. 



No. I — The Indian Genera of Melaniinae. 



By N. Annandale, D.Sc, F.A.S.B., Director, Zoological 

 Survey of India. 



It is convenient to separate the family Melaniidae or Tiaridae 

 into two subfamilies, the Melaniinae (or Tiarinae) and the Paludo- 

 minae, and to include in the former all the species with elongate 

 narrow shells. Among the Indian forms with this type of shell 

 only two genera have hitherto been generally recognized, namely 

 Faunus, de Montfort and Melania, Lamarck {=Tiara, Bolten) ; but 

 Melania has been divided into a number of subgenera, as to the 

 names of which there has been considerable confusion. My con- 

 clusions may be introduced conveniently by a key to the genera I 

 now recognize. Their status and limits will be discussed thereafter. 



Key to the Indian Genera of Melaniidae. 



1. Outer lip of shell forming a broad and prominent lobe 



defined above and below by well-developed canal-like 

 prolongations of the aperture. Operculum thick, with- 

 out spiral figure ... ... ... ... FauniiSi 



2. Outer lip not lobular, upper and lower canals of the aper- 



ture ill-defined or absent. 



A. Shell very small (less than i cm. high), hairy, 



sculptured with spiral incised lines only. Oper- 

 culum extremely thin, paucispiral, with the nu- 

 cleus eccentric. Foot produced into a filamentous 

 process behind. Marginal tooth of radula with 

 three sharp denticulations and a pointed process 

 near the base ... .. ••■ Mainwaringia. 



B. Shell large or of moderate size, as a rule without 



hairs, with at least a trace of longitudinal 

 grooves and ridges. Operculum at least moder- 

 ately thick. Foot without posterior process. 



1 See Kemp and Gravely, lud. Jour. Med. Research, VII, p. 252 (1919). .- / 



