MOLLTTSCA OF INDIA. 93 



Dental formula : — 



55 . 2 . 12 . 1 . 12 . 2 . 55 

 69 . 1 . 69 

 Specimens here described were sent me by Mr. 0. Collett from 

 Badulla, Ceylon. 



Ausienia planospira, Benson, was figured and described by me 

 in Vol. I. p. 149 (Plates XXXVI. & XXXVIII.) from specimens 

 obtained at Damsang, on the outer Bhutan Hills near Darjiling. I 

 have since examined other specimens from near Cbeung-tong, near 

 the junction of the Lachen and the Lachung rivers in Sikkim, at 

 10,000 feet, collected by Mr. W. Roberts. They present the same 

 characters ; radula exactly the same. It may be noted that the 

 generative organs (fig. 1, Plate XXXVIII.) show that the penis is 

 exactly of the same type as in Eurycldamys, quite simple : it differs 

 from this genus in possessing an amatorial organ : the shell-lobes 

 are very similar ; there is thus a departure in the genitalia from 

 Austenia, but, on the other hand, the teeth of the radula are like 

 MacrocMamys indica (Plate XVIII. figs 8-8 b). Tricuspid median 

 teeth, and the outer point of the laterals far below the inner one, 

 typical of Austenia. 



Under these circumstances it is not an easy matter to decide in 

 what genus this species should be placed. I was inclined to think 

 the simpler form of the male organ might be due to the smaller 

 size of the animal ; but this is not borne out by the form of the same 

 organ in shells even smaller, in which may be seen all the details 

 characteristic of MacrocMamys. For additional remarks see under 

 Austenia, further on. 



Microcystis dyalana, G.-A., from Borneo, described by me in the 

 P. Z. S. 1891, p. 37, pi. iv. figs. 4 a-c, is, in the type of the shell, 

 the form of the shell-lobes, and the male organ, remarkably like 

 these two Peninsular Indian species. Compare the latter organ 

 and the bulbous swelling at the point of connection of the vas 

 deferens. 



Subgenus Ratnadvipia, nov. 



(Alluded to in Presidential Address, Proc. Malacol. Soc. London, 

 vol. iii. no. 5, p. 253.) 



Ratnadvipia iekabtans, Pfr. (Plate LXXXV. figs. 1-8 a.) 



Vitnna irradians, Pfeiff'er, P. Z. S. 1852, p. 156 ; id. Mon. Hel. 

 vol. iii. p. 3 ; Reeve, Conch. Icon. pi. i. fig. 5 ; Hanley, Conch. Ind. 

 p. 29, pi. Ixvi. figs. 8, 9. 



Helicarion (sec. C) irradians, Theob. Supp. Cat. p. 24. 



HeUcarion irradians, Nevill, Hand-list, p. 15 ; Clessin, Nomen. 

 HeHc. 1881, p. 31 ; Tryon, Alan. Conch. 1885, p. 176, pi. 40. fig. 33. 



Original description [Plate LXXXV. figs. 5, 5 a'] : — " V. testa 

 depressa, amhitu subauriformi, tenui, lineis impressis confertim 



