154 Memoirs of the Indian Museum. [Vol. VII, 



convex anterior zone intervening between this band and the umbilical portion of 

 the columellar margin, the curvature of the lines of growth assumes a reversed 

 direction, with the convexity turned anteriorly or forward, and there are two or 

 three flat spiral bands, sometimes bifid, of about the same width as the intervening 

 spaces. The lines of growth, throughout the body-whorl, are crowded, fine, incon- 

 spicuous, strongly oblique, anteriorly retrocurrent, straight until quite close to the 

 anterior zone of accretions towards which they bend backwards and which they 

 traverse with a strongly sigmoidal curve as above described. 



The first half of the first whorl following the protoconch is of a uniform brown 

 colour, after which the pigmentation becomes differentiated in such a manner that 

 the primary ribs are white with chestnut patches at regular intervals, the intervening 

 spaces assuming a porcelain-blue to porcelain-purple colour, best seen in the case of 

 very fresh specimens. The contrasted whiteness of the non-maculated portions of 

 the ribs is partly due to the opaque appearance caused by the thickening of the 

 shell substance, while the bluish appearance of the intervals is partly caused by their 

 thinner substance allowing the porcelain-like effect of translucency ; nevertheless, 

 whenever the specimens are sufficiently fresh, it can be readily ascertained that the 

 colour effect is largely due to pigmentation of the intervals. The resulting appear- 

 ance is well rendered in Sowerby's illustration in Reeve's Monograph. The macula- 

 tions may be crowded as in the case of the specimen figured in Reeve's Monograph, 

 or else much wider-spaced. They are particularly crowded in some specimens from 

 the Andamans and from Balasore Bay, particularly wide apart in some specimens 

 from Puri, but the spacing varies greatly amongst specimens from one locality, and 

 even at different stages of growth in a single specimen. The maculations correspond 

 more or less exactly from one rib to another according to the direction of the incre- 

 ments of growth. As a rule there are no maculations on any of the intercalary 

 threads. In very exceptional cases they may be present, on the body-whorl, on 

 some of the threads of the second order situated at about the widest part of the 

 shell anteriorly to the level of the suture. The epidermis, when preserved, has the 

 appearance of a thin layer of yellow varnish which does not interfere with the general 

 appearance of the colour scheme. The pigmentation of the spire is invariably more 

 pronounced than that of the body-whorl. The loss of vividness of the colour decora- 

 tion with increasing growth in all forms of Dolium has already been commented on 

 by Reeve (Monograph, sp. n). 



The large semi-circular aperture, the more interior part of which is salmon- 

 coloured, becoming of a pure-white to bluish porcelain-like appearance towards the 

 edge, is quite simple posteriorly, while anteriorly it is terminated by a deep obliquely 

 disposed dorsal notch without any intervening canal. The columella forms an angle 

 of 125 to 130° with the base of the penultimate whorl. It is slightly oblique ante- 

 riorly towards the left of the shell. Its general direction throughout the greater part 

 of its length is straight with two slight bulges of which the more posterior one coin- 

 cides with the inward extension of the terminal zone of accretions, the more anterior 

 one with the sharply reflected edge of the columellar lip surrounding the narrow 



