II. MATERIALvS FOR A GENERIC REVISION 



OF THE FRESHWATER GASTROPOD 



MOIvLUSCS OF THE INDIAN 



EMPIRE. 



No. 4. The Indian Ampuixariidae. 



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

 D.Sc, Assistant Superintendent, Zoological Survey of India. 



The Indian species of this famih' present great difficulties to 

 the systematist. A large number of species have been described, 

 but between many of them annectant forms occur and some of 

 them exhibit considerable individual variability. Hitherto all 

 have been placed in a single genus, which has been variously 

 called AinpuUaria, Pila and Pachylabra, but recently one of us 

 has expressed the belief ' that Reeve's A inpullaria iiitx was prob- 

 ably worthy of generic distinction. Unfortunately very little is 

 yet known of the anatomy of this species, but both the shell- 

 characters and those of the radula certainly offer conspicuous 

 ditierences from those of Swainson's Ampullaria globosa (the type- 

 species of both Pila, Bolten and Pachylabra, Swainson) and its 

 allies. Indeed the only difficulty in the way of granting generic 

 rank to A. nux lay in the existence of the form referred to by 

 Nevill '^ as " Ampullaria nux, var. (? n. sp.)" As we have been 

 able to examine the radula of this form and find that it belongs 

 to the normal Pachylabra-type , while that of A. nux shows distinct 

 differences, we now feel justified in regarding the latter as the 

 genotype of a new genus, for which we propose the name Turbini- 

 cola in reference to its habits. We describe this genus here and 

 also the apparently intermediate form, which we regard as an 

 undescribed species, calling it after Nevill, Pachylabra nevilliana. 



Genus Pachylabra, Swainson. 



The shell is dextral,'* large or very large, moderately thick, 

 with a short globose spire and itself subspherical or broadly but 

 irregularly ovoid. Its mouth is large but not greatly expanded, 

 with a complete or almost complete but not very prominent peri- 

 stome, and with the outer lip as a rule slightly thickened. The 

 columellar callus is never expanded or incrassate. The sculpture 



1 Annandale, Joiirii. Nat. Hist. Soc. Siam I\", p. 2 (1020). 



2 Nevill, Ha>id List Moll. hid. Mus. II, p. 4 (1885). 

 " .Abnormal sinistral shells occur very rarely. 



