OF SOUTHERN INDIA. 481 
Looking upon the higher divisions of the Gastropoda, as noticed in our intro- 
ductory remarks, it will be seen that of the eight orders four* are represented 
in our South Indian cretaceous deposits, namely, the PutmonatTa, PRrosoBrancuta, 
OPISTHOBRANCHIA and ProsorocerHALaA. Of these the PRosoBraNcHIA, as might 
be expected, are the most numerous. 
The occurrence of four species of Hzzzcrpm in the highest, the Arrialoor 
beds, is of particular interest. Three of the species belong to the group Angystoma 
and one to Macrocyclis ; they all approach to Indian types of Hazrerpm, and one 
of them, Angystoma Arrialoorense, is very closely allied to the recent Helix 
Nilgirica. The identity of fossil with recent species is always a difficult point to 
be settled and often leads to disputes among naturalists, but it is a well known fact 
that the physical changes which have at different times taken place have often greatly 
affected the marine faunas, while the land fauna remained unaltered. I will not 
with our present meagre materials advocate the idea, that cretaceous species of land 
shells are still found living, but considering the absence of any largely developed 
tertiary deposits in the same districts, where the cretaceous beds of Trichinopoly 
occur, there would be nothing very novel in that suggestion, 
The PRosoBRANCHIA display a very great variety of forms. There are very few 
of their established families which have no representatives ; and some of them like 
the Crrrzipz, Voturipm, Purpvripz, Ceriraupx and Naricipz are particularly 
numerous. The crprazinz deserve special attention, because most of the species 
have, up to recent date, been referred to the oruzz, of which, however, there seems 
to be not a single cretaceous species as yet recognised with sufficient accuracy. 
Equally interesting is the occurrence of members of the family Vercyorroprpx 
and Cancertarup#; the Lrrrormip# have also been found largely represented, 
and the genus Littorina and others were unjustly excluded by @Orbigny from 
the cretaceous deposits, as they are already in the older secondary formations, 
and even in the paleeozoic period, numerous, and most probably more varied in 
form than we meet with them in the cretaceous and tertiary beds. 
Some genera like Hrato, Dipsacus, Oniscia, Cythara, Trophon, Euclia and 
Narona, Teinostoma, Vitrineila and others have now been first noticed as occurring 
in cretaceous deposits; others, like Cyprea (and allied forms) Rapa, Rissoa, 
Rissoina, Lnttorina, Velutina and others have been fully established in their 
geological importance with regard to the same period. 
Of the OPISTHOBRANCHIA the family Acr#onipz is comparatively very largely 
represented, there being no less than 24 species known from the cretaceous deposits 
of South India. Among these two species of Acteonina, one of Bullinula, two 
of Ringicula and three of Huptycha deserve a special notice. 
The PRosopocHPHALA with their family Dzyrazipz have been treated at 
considerable length, but they exhibit no particular forms; only four species occur, 
belonging to the genera Dentalium, Antale and Fustiaria (n. gen.). 
* The other four being the NEUROBRANCHIA, HETEROPODA, POLYPLACOPHORA and PTEROPODA. 
OR 
