42 Records of the Indian Museum. [Vol. XIX, 



Key to the Indian Genera, species of which have been assigned to 



Bithynia, Leach. 



1. Operculum spiral on botJi surfaces, with the nucleus 



eccentric. Whorls of shell more or less tumid and 

 body-whorl very large ; umbilicus closed or rimate ; 

 columellar fold ridge-like but by no means promi- 

 nent ; central tooth of radula with latero-basal denti- 

 culations in a series on either side ... ... Anniicola 



{Alocinma). 



2. Operculum concentric, or mainly so externally, with the 



nucleus central or sub-central, almost smooth inter- 

 nally. 



A. Shell conspicuously perforate, turbinate, ornament- 



ed with strong spiral ridges ; peristome con- 

 tinuous, prominent, uniform ; central tooth of 

 radula with a single blunt, downwardly-directed 

 lateral process at each side ... ... MysoreUn.^ 



B. Shell broadly but shallowly umbilicate, with a 



broad oblique groove proceeding downwards 

 from the umbilicus to the lower margin of the 

 mouth ; sculpture consisting of fine spiral 

 grooves ; central tooth of radula as in Aninicola Sataria, nov. 



C. Shell narrowly umbilicate or subumbilicale, with 



a narrow groove descending obliquely from um- 

 bilicus but not reaching margin of mouth ; 

 columellar fold forming a sharp, prominent 

 ridge continuous with outer lip ; outer lip hardly 

 thickened ; central tooth of radula as in 

 A77inicola ... ... ... .. Bitliynia. 



D. Shell resembling that of Bitliynia, but with the 



columellar fold greatly thickened and the whole 

 outer lip more or less incrassate ; a varix often 

 present on the body-whorl ; central tooth of 

 radula as in /4w;zzco/a ... ... ... Hydrobioides. 



Two genera in this key [Mysorella and Sataria) are, so far as 

 we know, monotypic. Mysorella has recently been described by 

 Col. Godwin- Austen,' while Sataria is here described as new ; but 

 the type-species of both have long been known, Hydrobioides was 

 first erected as a subgenus of Bithynia by the late Mr. G. Nevill.^ 

 I have recentl}^ discussed it at some length.* Dr. Baini Prashad* 

 and I have also, still more recently, proposed a new subgenus 

 (Alocinma) of Amnicola, Gould and Haldeman, to contain certain 

 Indian and Persian species. A large proportion of the Indian, 

 species hitherto assigned to Bithynia belong to this subgenus, more 

 in feict than can be retained in the former genus. The species des- 

 cribed by Mr. Preston, with those recently described by myself, 

 ma}'^ now be identified generically as follows : — 



To the genus Amnicola and the subgenus Alocinma I attribute 

 the following :— 



Bithynia travancorica, Benson; B. suhpulchell a, ^qv'iW; B. 

 inconspicua , Dohrn ; B. orcula, Frauenfeld ; B. laevis, 



1 Godwin-Austen, Rec. Ind. Mus. XVI, p. 431 (1919). 



2 Godwin-Austen, Rec. Ind. Mus. XVI, pp. 211, -J3i (1919). 



3 Nevill, Hand List Moll. Ind. Mus. II, p. 42 (1884). 

 * Annandale, Rec. Ind. Mus. XIV, p. 117 (1918). 



^ Annandale and Prashad, Rec. Ind. Mus. X\'III, p. 23 (1919). 



