1807.] Contributions to Indian Malacology, 59 



Shell globose, obliquely oval, solid, closely obliquely and rather 

 sinuously wrinkled, sometimes bearing spines, covered with a dark 

 epidermis. Colour generally dark olive with minute yellow specks, 

 occasionally with oblong splashes of yellow below the suture ; these 

 generally curve backwards, and are sometimes, but rarely, of large size. 

 Some shells are surrounded more or less obsoletely with yellow bands. 

 Beneath the epidermis the shell is pink or bluish spotted with white. 

 Young specimens are frequently pink, with yellow specks, in front of 

 each of which is a black streak like a shadow. The spire is barely 

 exserted, apex obtuse, and generally eroded, the erosion extending 

 frequently down the spire, and often a portion of the outer surface of 

 the last whorl itself is wanting ; suture raised, compressed. Whorls 3, 

 the upper ones frequently wanting, but when present, flattened or sub- 

 concave. Last whorl concave and compressed against the suture above, 

 then either carinate above the periphery and bearing short subdistant 

 spines, or else obtusely, more or less obsoletely angulate. Below it is 

 always rounded. Aperture milky within, peristome semioval, columellar 

 area flat, yellow or dirty white, minutely denticulate, except in front, 

 and having a prominent re-entering tooth just above the middle. 

 Operculum pinkish white outside, exterior margin black, red inside. 



The nearest ally to this form with which I am acquainted in N. 

 obscurata, Rccluz, which has a more expanded mouth, and more deep- 

 ly emarginate columellar area, the whorls appear also rather different- 

 ly shaped above. 



The present species is eminently variable. The type occurred in abun- 

 dance close to the beach in a small stream which descends from the 

 hills close to Cape Negrais ; specimens were especially abundant in a 

 brackish pool at the beach, spinous and spineless shells occurred mixed 

 together, and the presence or absence of spines is evidently of no im- 

 portance. The spineless variety from Port Dalhousie was found in the 

 salt water of the Bassein river, abounding along the strand between 

 tide marks. 



To illustrate the variation of this species, several specimens have 

 been figured. 



Specimens collected by Mr. Theobald in Arakan illustrate the gra- 

 dual passage, by absolutely insensible gradations, of this form, into the 

 very distinct N. relifem, Bens, of the Ganges delta. 



