70 Contributions to Indian Malacology. [No. 2, 



striated beneath. Spire depressly conoid, with convex sides, the 

 apex slightly acuminate and papillar; suture hut little impressed. 

 "Whorls 7J, convex, closely wound, slowly increasing ; the last sharply 

 keeled, flatly convex beneath, marked in nearly adult and sometimes 

 in full grown specimens, with two or three small pits of variable 

 form, opaque from corresponding internal calli, and generally arranged 

 in an oblique line opposite to the mouth. Aperture oblique, sub- 

 rhomboidally lunate, 3 times as broad as high ; columella furnished in 

 young specimens with a more or less rudimentary spiral lamina 

 running up the whorls, which is obsolete in adult shells. Peristome 

 thin, slightly curved forwards at the base ; margins distant, columellar 

 margin very oblique. 



Millem. inch. 



Major diameter, 11 0.44 



Minorditto, 10 0.4 



Axis, 6i 0.26 



Aperture 5J millem. broad, scarcely 2 high. 



Animal similar to that of N. helicifera. 



Habitat — Akoutoung, Pegu — not rare. 



The close relation of this species to the last is unquestionable ; 

 besides resembling it in general form, texture, and sculpture, and in 

 the characters of the animal, young specimens possess a similar 

 columellar fold, and indentations on the lower surface somewhat 

 resembling those of N. helicifera, though less deep and more opaque. 

 Both these characters, however, appear to become obsolete in adult 

 specimens of the present form. The two species are easily distin- 

 guished by the absence of the columellar lamina in adults of N. 

 mamillaris, which may also be recognised by its acuminate apex, 

 lower spire and flatter base. 



7. N. Basseinensis, n. sp. 

 Shell minutely perforated, globosely trochiform, subcampanulate, 

 thin, horny, closely, sharply and arcuately costulated above, the costu- 

 lations passing over the periphery to the under surface, which is 

 smooth, shining, and radiately striated. Spire obtusely conoid, with 

 convex sides ; apex obtuse ; suture slightly impressed. Whorls 7, 

 slightly convex, closely wound, slowly increasing ; the last not de- 

 scending, flatly convex beneath, more tumid near the mouth, keeled 



