76 Contributions to Indian Malacology. [No. 2, 



and below. Spire quite flat, apex not rising above the surface, suture 

 impressed. Whorls 6| — 7, narrow and closely wound, slightly convex 

 above ; the last much broader, rounded at the periphery and beneath, 

 descending abruptly close to the mouth. Umbilicus shallow, exposing 

 all the whorls. Aperture more nearly horizontal than vertical, sub- 

 circularly lunate. Peristome slightly thickened, expanded throughout, 

 margins joined by a rib, from the centre of which a lamina sometimes 

 runs up to the parietal plication, but is frequently interrupted a short 

 distance within the aperture, and is always thicker and higher near 

 the mouth than further back. Parietal plication consisting of a verti- 

 cal lamina in front, and a second, slightly oblique, just behind the 

 first, giving out the interrupted lamina running to the aperture from 

 the top, and a shorter horizontal lamella from the bottom ; the hinder 

 with small re-entering supports above and below. Beneath both is a 

 narrow free thread-like horizontal lamella. Palatal teeth 5 : 1st, 2nd, 

 3rd and 5th horizontal, 4th vertical and stouter than the others ; 1st 

 and 2nd longer than the remainder. 



Mill em. inch. 



Major diameter, 16 0.65 



Minor ditto, 13 0.52 



Height, ., 4J 0.18 



Habitat — Prome : rare. 



Of this unquestionably distinct species but 3 or 4 specimens were 

 found by Mr. Fedden and myself. Both the external form and plica- 

 tion differ from those of all allied species. It is especially distinguish- 

 ed by its rounded periphery, wider last whorl, and its irregular 

 non-decussated sculpture externally, and internally by the double 

 parietal lamina. 



Section ? 



15. H. polypleuris, n. sp. 



Shell openly umbilicated, trochiform, rather solid, white, (probably 

 horny in living specimens,) obliquely and closely costulatecl. Spire 

 conoid ; apex rather obtuse ; suture impressed. Whorls 6, convex, 

 slowly increasing ; the last not descending, surrounded by a raised 

 'thread-like keel, convex beneath, and somewhat sinuously radiately 

 costulated around the deep and pervious umbilicus. Aperture oblique, 



