>42 



Records of the Indian Museum. 



[Vol. XXII, 



as long as the body- whorl. The outer lip turns inwards above and 

 meets the inner callus at an angle slightlv greater than a right 

 angle. The columellar border is arched, prominent and thick, with 

 its lamellar structure well developed. The umbilicus is almost 

 closed but the channel running forward from it well defined. The 

 inner lower angle of the lip is strongly developed. 



_'^_^^^\ 



Fig. I. — Tj'pe-shell of Digoniostoma textiim. 



The operculum is large, subrhomboidal, moderately thick, testa- 

 ceous-translucent when fresh but soon becoming white and dull. 

 There is a very delicate brownish periostracum on the external sur- 

 face, which is rather deepty concave in the central region. The 

 nucleus is subcentral, but situated slightly in front of the middle 

 point. The sculpture is poorly developed but several faint concentric 

 ridges can be detected round the periphery, while the nucleus re- 

 tains traces of a spiral origin. The internal surface is convex and 

 faintly granular, with a rather broad flattened border on the outer 

 margin. 



The radula is like that of a typical Bithynia. The specific 

 characters of the teeth are well shown in fig. 2. 



Fig. 2. — Radul 



Digoniostoma textniii. 



The external soft parts are dull greenish speckled with yellow. 

 The feet, snout and tentacles are normal, the foot is rather shorter 

 and the operculiferous lobe larger than some species. The male 

 organ is densely pigmented, long, coiled, tapering and produced to 

 a very fine point. Its subsidiary appendage is colourless, long and 

 slender, cylindrical and with a simple cup-shaped depression at the 



