K>22.] N. Annandale : Indian Planorbidae. 36r 



Genus Gyraulus Agassiz (1837). 



1919. Gyraulus. Annandale & Prashad, Rec. Ivd. Mus. XVIII, p. 52. 

 1921. Gyraulus, Germain, op. cit., p. 8. 



Most of the smaller Indian Planorbidae are comprised in this 

 genus. The species I have examined are G. euphraticus Mousson, 

 G. convcxinsculus (Hutton), G. labiatus, G. cantori and G. rotula 

 Benson, but Germain also assigns to the subgenus (as he conceives 

 it) G. himalayanus (Hutton). I think he is wrong in assigning 

 cantori to Segmentina, though he follows Benson and other early 

 Indian conchologists in so doing. 1 



The type-species of Gyraulus is Planorbis a/bus Midler, which 

 is widely distributed in the Palaearctic Region. 



Genus Diplodiscus Westerlund (i8<)/). 

 1921. Diplodiscus, Germain, op. cit.. p. 7. 

 I have not seen any Indian species of this genus, but Germain 

 assigns to it Benson's Planorbis hyptiocyclos from Ceylon. Accord- 

 ing to Simroth * the type-species {Helix vortex L.) has the male 

 organ of the same type as that of Gyraulus, viz. P. albns Miiller. 



Genus Hippeutis Agassiz (1837). 



1921. Hippeutis, Germain, op. cit., p. 



1921. Hippeutis, Annandale and Prashad, op. cit.. p. 584. 



Dr. Prashad has been able to confirm our recent identification 

 of Benson's P. umbilicalis as belonging to this genus by an examina- 

 tion of the anatomy of a European species. 3 The male organ of 

 the latter resembles that of Indoplanorbis except that the penis is 

 coiled inside the upper part of the penis-sheath. This character is 

 still more strongly marked in H. umbilicalis, in which, however, 

 the praeputium is apparently longer. The radulae of the two 

 species also agree in general characters and in particular in having 

 the lateral teeth arranged in pairs as if twinned. 



The only Indian species I have seen is Planorbis umbilicalis 

 Benson. P. sindicus Benson also probably belongs to the genus, 

 hut his P. cacnosus is a Segmentina. 



Intha, gen. no v. 



In this genus the body-whorl, though relatively smaller than 

 it is in Hippeutis, completely embraces and occludes the rest of 



1 Sec Annandale and Prashad, Rec. Ind. Mus. XXII, p. 583 (1921). 



2 Simroth, op. cit., p 503. 



'■'■ The specimens examined belong to a very large and well-developed phase 

 from the month of the Var in the south of France. The}' seem to me, however, 

 l<> be at leasl generically identical with typical shells of //. fontanus, the type- 

 species, from England which Mr. Tomlin has been kind enough to give me. My 

 French shells apparently belong to the form called euphaeus Hourg. by Germain 

 in his Mnllnsques de la France, torn. II (1913). 



