70 Contributions to Indian Malacoloqy. [No. 2, 
striated beneath. Spire depressly conoid, with convex sides, the 
apex slightly acuminate and papillar; suture but little impressed. 
Whorls 74, 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- 
thomboidally 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running up the whorls, which is obsolete in adult shells.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,.........s0ss00e« TE 0.44 
Minion Gatto) wr stcssisinncroseeeh joae 10 0.4 
Axisiiewonlin. wat aa. cms! 6} 0.26 
Aperture 5} 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 NV. heliczfera, 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 WN. 
mamillaris, which may also be recognised by its acuminate apex, 
lower spire and flatter base. 
7. N. Bassrrvensis, 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 
