590 Records of the Indian Museum. [Voi,. VIII, 



The jaw is straight in front with a central projection not very 

 convex above, and not unlike that of Khasiella dinoensis, n. sp. 

 Central tooth and admedians of usual form, but the marginals are 

 noticeable, being long, curved and scimitar-shaped, an important 

 character. The dental formula is 22.7.1.7.22 or 29.1.29 No transi- 

 tional teeth, the seventh admedian is followed by a curved unicus- 

 pid tooth. 



This radula in the form of the teeth is similar to that of M. ? 

 beata, G.-A., from the Dafla Hills (shell figured in Moll. Ind., plate 

 cviii, figs. I, ja, 16). This locality is interesting being not far 

 distant, 150 miles to the west. The shell lobes also are similar 

 (vide Moll. Ind., p. 263, plate cxxv. figs. 6b, 6c), and the jaw is of 

 the same type^ not arched but straight in front. Neither in beata 

 were the generative organs seen entire, only the amatorial organ. 

 There is consequently a doubt regarding the male organ, judging 

 from the broken parts of it, of which I made careful drawings, there 

 was no sign of the coiled caecum, a typical character and always 

 present in true Macrochlamys. In consideration of this and 

 the teeth of the radula it cannot be placed in that genus. If 

 anatomy is to prevail in classification and the great variation in 

 more than one internal organ be considered of greater weight than 

 mere shell form^ a new sub-genus is a necessity. 



Rotungia, gen. nov. 



Shell globose, thin and membranaceous, last whorl ample, 

 subangulate on the periphery, much flattened above and ex- 

 cavated, whorls rapidly increasing. Animal : linear mucous gland, 

 right and left shell lobes present. Extremity of foot on the dorsal 

 side much flattened and leaf-like, a central groove with lobes on 

 right and left. 



Radula like Macrochlamys. 



Generative organs: penis simple with short flagellum, sper- 

 matheca short, amatorial organ large. 



Type: R. williamsoni, n. sp, 



Rotungia williamsoni, n. sp. 

 (Plate li, figs. 5, 5a; pi. liii, figs. 1-5.) 



Locality. — Upper Rotung, Abor Hills, 6-i-i2, No. 5934-37 (5. 

 Kemp). 



Shell very thin, horny, smooth and shining, imperforate, 

 flatly globose ; sculpture : on the flat large whorl above are indis- 

 tinct transverse regular lines of growth ; colour ochraceous brown 

 with a golden sheen when animal fills the shell ; spire very flat, 

 apex scarcely raised above the last whorl ; suture deeply de- 

 pressed, excavated ; whorls 5, apex closely wound, increasing rapid- 

 ly, periphery sinuately rounded, flattened next the keel above it, 

 which commences on the 3rd whorl; aperture broadly ovate, sub- 



