138 Records of tlte Indian Museum. [Vol. XIY. 



Asia in liaving a horny operculum. He, therefore, calls the latter 

 Pachylabra, Swainson. Preston calls them Pila, Bolten. I am not 

 convinced, however, that the generic division is necessary, and in the 

 case of generic names I am not in favour of disinterring those which 

 have long been buried and forgotten, even if this be done with due 

 rites and in accordance with law. 



Only a single species of AmpuUaria was found in the Inle basin 

 and none were obtained, either recent or fossil, on the He-Ho plain. 



AmpuUaria winkleyi, Pilsbry. 

 Plate xii, fig. 10. 



1901. AmpuUaria Winkleyi, Pilsbry, Proc. Ac. Nat. Sci., Philadelphia, LIU p. 189, 



pi. V, figs. 2, 3.' 

 1915. Pila winkleyi, Preston, op. cit., p. 103. 



This species is somewhat plastic. In specimens from streams run- 

 ning out of hot springs on the western side of the lake, the shells are 

 not longer than 45 mm. and have the mouth narrow, while those from 

 flooded rice-fields in the same district reach 65 mm. and have the mouth 

 somewhat broader, though a little narrower than in Pilsbry's figure. 

 The latter specimens are also paler in colour. Specimens from the 

 edge of the Inle Lake and from the Yawnghwe river are intermediate. 

 Probably the most characteristic and the most constant feature of the 

 species is the concentric sculpture of the columellar side of the scar 

 of the operculum. This is constant in a large series and differentiates 

 the operculum from those of A. conica, Gray and A. compacta, Reeve, 

 in both of which the sculpture is irregular and without definite pattern. 



As in many other species, the resting-stages in growth are often 

 marked by distinct ridges on the shell, and in some specimens from 

 two to four distinct regions can be distinguished on the body-whorl 

 in this way. In the specimen figured on pi. X there are four regions 

 of the kind and the last one is much paler in colour than the remainder 

 of the shell. 



The species was described from Henzada, Pegu. According to 

 Pilsbry it is somewhat allied to A. begini, Morlet, a species distributed 

 through the whole of Cambodia and on the lower Mekone. 



Pelecypoda. 

 Order TETRABRANCHIA. 



Family UNIONIDAE. 

 Genus Physunio, Simpson. 



1900. Physunio, Simpson, Proc. (J. S. Nat. Mv.s., 22, p. 830. 



Two species from the Inle basin that represent this genus both be- 

 long to the section Physunio, s.r,. 



f\ 



