140 Journal of the Asiatic Society of Bengal. [N.S., XV, 
Measurements. 
Mauritius Mergui 
specimen. specimens. 
fs ‘5 7 
Height 37°5 mm. 50 mm. 43 mm. 
Thicknes a aa 30°55, 25 (Cs, 
Dorso- rentill dia- 
meter 26 eM eat se 
Ratio 1:0°63:058 1:0°61:0°52 1:0°58:051 
Number of denticu- 
lations in tle? ein 25 29 27 
Number of den 
lations in eehogiiitinx lip 23 22 25 
Variability —In both the Mergui specimens, the fossula is 
relatively narrower than in the specimen from Mauri itius. This 
is due partly to the fact that, in the Mauritius specimen the 
columella is almost vertical, ‘diverging therefore somewhat 
abruptly from the obliquity of the base of the penultimate whorl, 
and thereby contributing to increase both the width and depth 
of the fossula, while in the Mergui specimens, it remains more 
distinctly oblique. Moreover, throughout the entire length of 
the Siniaailen, a the denticulations spread internally over a 
wider area in the Mauritius specimen than in those from 
Mergui: this tether circumstance being connected with the fact 
that the Mauritius specimen is relativly more convex, with a 
relatively greater dorso-ventral diameter. The terminations of 
the interstices between the denticulations are more abruptly 
demarcated on the ventral surface in the case of the Mauritius 
specimen, than of those from Mergui. 
o far as can be judged from the material available in 
Calonttn, these slight differences may indicate that the Mergui 
shells constitue a local race. — Devers heless, there is reason to 
think that th nstant for, in the illustration 
representing the ventral sae of a Mauritius specimen, pub- 
lished in G. B. Sowerby’s Thesaurus Conchyliorum, and repro- 
duced in Roberts’ pia the columella is disposed exactly 
as in the Mergui shells. 
Of the two Mergui specimens, one is distinctly, the other 
wort more elongate than the Mauritius shell. 
rison with a vitellus—As may be gathered 
from she error of identification alluded to at the commence- 
ment so this note, this shell exhibits a certain superficial resem- 
i. pp. 205-206). In the case of Cyprea vitellus, the brown 
or buff layer is deposited first, and the white spots are local 
accretions of opaque white enamel, analogous in effect to the 
