362 Records of the Indian Museum. | Vol,. XXIV, 



the shell in such a way that the spire is entirely concealed, except 

 in so far as it can be detected by transparency. The shell is very 

 minute and has few whorls, which increases in size rapidly. Those 

 of the spire are cylindrical, but the body-whorl is flattened below 

 and has the form of a flattened conoid slightly truncate above. 

 The outer lip arises in the middle of the upper surface and forms 

 a small lobe at its point of origin. The aperture is large and 

 very oblique but with a cordate outline. There is a well-devel- 

 oped simple callus on the inner lip, but internal ridges are com- 

 pletely absent. The lower surface is narrowly umbilicate. The 

 external surface is practically smooth. 



The animal is remarkable externally for the large upper and 

 lower lobes into which the mantle is divided. The pseudobranch is 

 poorly developed. The jaw is broken up into many horny teeth 

 as in Segmentina and Ancylus. The radula is very minute but 

 appears to be quite normal. The male organ resembles that of 

 Planorbis, except that the penial bulb is relatively very large. 



Type species. J nth a capitis, sp: nov. 



Intha capitis, sp. nov. 



The type-species may be described here very briefly. I hope 

 to discuss it at greater length shortly in a second paper on the 

 Inle fauna. 



Shell minute (2*5X2X1 mm.), colourless, hyaline but rather 

 thick, highly polished, with the upper surface somewhat convex, 

 with about 3 whorls ; a minute/pinhole on the upper surface at the 

 base of the outer lip, which bears a minute lobe at its point of 

 origin. Aperture very large ; the callus of the inner lip broad and 

 rather opaque, extending outwards on the shell beyond the lip, 

 but not greatly thickened. Lower surface quite flat, very narrowly 

 umbilicate. External surface with fine curved vertical striae ; no 

 spiral sculpture. 



Habitat. He-Ho and Inl6 valleys (3000-3800 ft.), Southern 

 Shan States, Burma (recent and subfossil). 



Type-specimen. No. M 11998/2, Zoological Survey of India. 



Segmentina Flemming (1828). 



1919. Segmentina, Anniiiulale nndt IV.i.-ih.ul, op. cit., p. =;<>. 

 1921. Segmentina, Germain, op. cit., p. 



The Indian species examined are P. calathus and P. caeuosus 

 Benson and an undescribed species from the Southern Shan States. 

 Benson's P. trochoideus also undoubtedly belongs to it. In P. 

 caenosus the internal ridges are often poorly developed and con- 

 cealed by the opacity of the shell, but at least traces of them can 

 always be detected on close examination. 



The type-species is the Palaearctic Planorbis nitidus Miiller, 

 to which P. calathus is closely related. 



