112 Proceedings of the Asiatic Society. [ May, 
portion of it lies rolled in on the right side behind the mouth. 
It is composed of between 260-280 transverse rows of teonioglossate 
teeth, the formula being 3.1 . 3. (see fig. 4). The centre tooth is 
somewhat longer than broad, rounded above, strongly emarginate at 
the sides, and less so at the base. The upper edge is very strongly 
inflected, with 7 denticles of which the median one is the largest, 
(see fig. 5). Along the concave sidesruns a very thin, raised la- 
mella, and the projecting corners of the base are also bent upwards. 
The lateral teeth follow below each other under a rather steep 
angle ; all have the upper edges strongly inflected, each having the 
median denticle the strongest and obliquely projectin®, the outer 3 
denticles on each side decreasing in size ; on the outermost tooth 
the latter are sometimes hardly traceable. The general shape of 
the first lateral tooth is obliquely qradrangular, posteriorly deeply 
emarginate and with the posterior half of the upper edge thinner 
and a little longer. The bases of the two outer lateral teeth are 
obliquely, and more or less obtusely, pointed. 
The teeth of C. carinatus, and its varieties, are perfectly similar 
to those of Syhadrensis, except that the median denticles of the 
teeth are a little stronger and more pointed, as compared with the 
adjoining lateral denticles. 
‘When we compare the general anatomy of Cremnoconchus with 
that of Littorina,* we find that both are almost perfectly identical. 
Prof, Troschel, in the above noted communication (p. 94), charac- 
terized Cremmnoconchus as possessing ap. umbilicated shell and the 
median teeth of the radula without laterally raised lamella, while 
Littorina has, according to the same author, a non-umbilicated shell 
and the median teeth with lateral lamelle. The statement relating 
to Cremnoconchus, is, however, evidently an oversight on the part 
of Prof. Troschel. The median teeth of Cremnoconchus have, as 
already noticed, laterally raised lamelle, and the shell is either 
umbilicated or not ; as is clearly shewn by Cremnoconchus carinatus, 
andits varieties. In the two points alluded to, the genus, therefore, 
perfectly agrees with Littorina, and it is indeed not easy to find out 
sufficiently distinctive characters between the two. 
_ * J have examined in connection with this subject Littorina melanostoma, and 
two other species very closely allied or identical with undulata and intermedia. 
