1865.] Contributions to Indian Malacology. 67 



Millem. inch. 



Major diameter, 11| 0.46 



Minor ditto, 10 0.40 



Axis, 6 0.24 



Aperture 6 millem. broad, 4 J high. 



Habitat — Akoutoung on the Irawady, below Prome, Pegu. 



This species may be distinguished from its numerous allies of the 

 Macrochlamys section by its blunt angulation at the periphery and its 

 dull lustre. Its nearly vertical mouth amply serves to shew its dis- 

 tinction from N. honesta, Gould, which shell moreover is more polished, 

 and differs in several other particulars. 



3. N. hypoleuca, n. sp. 



Shell openly perforated, depressed, very thin, smooth, polished, 

 homy ; dark brown above ; lighter, frequently white below ; faintly 

 striated, obliquely above, radiately below, with extremely fine con- 

 centric microscopic markings, which are frequently obsolete. Spire 

 very little raised ; apex rather obtuse ; suture impressed, sometimes 

 sub-marginate. Whorls 5, rather convex above ; the last rather 

 broader, rounded beneath, not descending. Aperture lunate, the 

 breadth exceeding the height, nearly vertical ; peristome acute, 

 straight ; columellar margin descending with an oblique curve, scarcely 

 reflexed, 



Millem. inch. 



Major diameter, 12 0.48 



Minor ditto, 10J 0.42 



Axis, 6 0.25 



Habitat — Akoutoung, Pegu. Scarce. 



Near N. causia, Bs., but larger, more depressed, and with far finer 

 microscopic spiral sculpture ; so fine indeed that it is difficult of detec- 

 tion even under a powerful microscope. H. hypoleuca may be re- 

 cognised by its pale base, and dark horny colour above, and by its open 

 perforation. 



A small form, perhaps identical with the above, but only 5 or 6 

 millemetres in diameter, is common in northern Pegu. I had con- 

 founded it with N. causia, Bens., but Mr. Benson informs me that 



