MOLLUSCA OF INDIA. 231 



inhabiting the mountains of Sikkim. Conchologically they have 

 been there sufficiently long to become specifically distinct ; this 

 apphes more especially to species that are vegetable-feeders and 

 crawl about on shrubs, like so many of the genus Macrochlamys. 

 A certain number, such as the operculated forms, although subjected 

 to a like water transport, do not become introduced. Living exclu- 

 sively, or as a rule, on rock-surfaces, they cannot so easily become 

 settlers in a delta, where conditions of swamp, mud or sand, prevail. 

 However, Cyclophorida^ of the Kajmahal Hills may possibly be the 

 descendants of migrants from the northward. 



In conclusion, I trust that the anatomical details of the numerous 

 species now examined and published will give malacologists a better 

 iudication of their generic position, and in the case of some species 

 render that position less uncertain than it has hitherto been. Such 

 details are the only sure guide to an exact knowledge of the range 

 of genera and species on which speculations relating to their distri- 

 bution can be with certainty founded. So far as the Land Mollusca 

 re concerned, I think there are sufficient grounds for the establish- 

 ment of very different zoological regions in this part of the world, 

 and I hope, after the examination of certain species I am endea- 

 vouring to obtain, I may be able to work out this subject in 

 i^reater detail. 



EXPLANATION OF PLATE CL 



Bensonia camura, Benson. Sikkim. 

 Fig. L Shell, natural size, 

 la. Ditto, X •2-5. 



2. Mantle-edge and right dorsal lobe, X -5. 

 '.i. Extremity of foot, X 8. 



4. Mantle-edge and anterior part of visceral sac, X ■4-,5. 



5. Genitalia, removed from the animal, X 4'5. 



5 a. Ditto, seen from right side before removal, X 4'.o. 

 5/;. Ditto, seen from left side before removal, X 4"5. 



6. Jaw, X 12. 



7. Radula, part of, X 368. 



ca, C£ecum ; rec, rectum ; r.o, renal organ ; ov, oviduct ; P, penis ; v.d, vas 

 deferens; k, kalk-sac; sp, spermaiheca; B, amatorial organ or dart- 

 sac; rmP, rniD, retractor muscles of penis and dart-sac. 



EXPLANATION OP PLATE GIL 



Balingia bhutanensis, n. sp. Bhutan Hills. 

 Fig. 1. Shell, natural size. 



1 a. Ditto, front view, x 2'5. 



2. Mantle-edge, showing dorsal lobes seen from above, X 4a. 



2 a. Ditto, showing dorsal lobes viewed from below, x 4'0. 



3. Portion of peripodial margin of the foot, x 8. 



4. Generative organs, x 4'0. 



4 a. Ditto, male organ, reverse side, X 4'.'>. 



4 /). Ditto, albumeu-gland &c., X 4'5. 



5. Jaw, X 12. 



6. Teeth of the radiila at different parts of the row, x 368. 



