II J Records of the Indian Museum. [Vol. XIX 



Idiopoma to a Burmese species, V. henzadensis. These characters 

 however, are adaptive and are not found either in all species of 

 the group, or even in all individuals of the species in which they 

 are present. They are connected with the habit of aestivation in 

 drying mud, the Viviparae dissimiles being found mainly in bodies 

 of water liable to desiccation. The species are widely distributed 

 in the plains of Peninsular and North-Western India and in the 

 drier regions of Burma. 



Viviparae sindicae. Shells of this group are distinguished 

 by their very pale colour, by the absence of distinct spiral bands 

 and by the thinness of the operculum, in which the muscular scar 

 is very feebly developed. Nothing is known of the anatomy. 



The only Indian species is V. sindica (Nevill) from Sind, but 

 another occurs in Seistan. Kobelt has caused great confusion in 

 the Conch. Cab. by basing his description ' and figures of this form 

 on the type-series of Nevill's Paludina dissimilis sindica, which I 

 regard as a distinct species, and conversely describing and figuring 

 specimens from Seistan as sindica. His hilmendensis is, therefore 

 an absolute synonym of sindica (Nevill). I propose for the Seistan 

 species the name V . helmandica. 



Genus Lecythoconcha, nov. 



The shell is of large, sometimes of relatively gigantic size, 

 but never very thick ; it is smooth or with obscure and never very 

 prominent sculpture and always translucent when fresh ; it is 

 globose in form , with broad swollen whorls, and often bears a striking 

 superficial resemblance to that of Pachylabra (AmpuUariidae). 

 The colour is uniform or nearly so, as a rule rather bright olive 

 green, often with irregular blackish longitudinal lines. The aper- 

 ture is large and patent, subcircular or broadly ovate. The colu- 

 mellar fold is not strongly developed, the umbilicus narrowly per- 

 forate and the outer lip thin. 



The operculum is large, thin, horny, stiff and brittle. Ex- 

 ternally it is marked with fine but prominent concentric ridges and 

 bears a deep, funnel-shaped pit in a subcentral position. On the 

 internal surface this pit is represented by a smooth, prominent 

 rounded boss, which is surrounded by a smooth or minutely granu- 

 lar area representing the muscular scar. 



The animal differs from that of Vivipara in the greatly thick- 

 ened and very muscular free edge of the mantle, the sphincter 

 muscle running along it is verj- prominent and unusually well 

 developed. There are three marginal processes in the young, but 

 none in the adult. 



The radula is identical with that of Vivipara. 



Type-species. Paludina lecythis, Benson. 



Geographical Range. The range of the genus probably ex- 

 tends from Manipur (and possibly Sylhet) in the west through 



^ This description was originally published in Nachr. Malak. Ges. LX, 

 p. i6i (1908). 



