OF SOUTHERN INDIA. 249 
There is a good deal to be said as regards the genera, which should be admitted 
into this family, although this subject has been lately admirably treated by Deshayes 
in his new edition of the Paris fossils. This conchologist quotes four genera only, 
namely, Solarium, Discohelix, Bifrontia, and HLuomphalus. We think, however, that 
the varieties of shells seem to make a larger number, and some alterations in the 
nomenclature, of the genera necessary. Not being, however, in possession of all 
the desirable materials, which would be required to make such alterations really 
of any good service, we must confine ourselves to a few remarks, which, we trust, 
will at least lead a step further towards clearing up the confusion at present exist- 
ing among the genera of this family. The recent Solaria of Lamarck have been 
divided by H. and A. Adams into three genera. The number of fossil species of 
the Sozarmp# is very large, and the following may at present serve as a short 
review of the different generic forms belonging to this family. 
1. Solari hae, Lamarck, 1799, as restricted for the depressed, sub-conical forms, 
possessing a flat, Pucispiral operculum. 
la. Philippia, Gray, 1840, differs from Solariwm only by its smooth shell. 
Gray places the genus in the Zrocuzpx, but if the shell is not pearly within, 
H. and A. Adams’ classification is preferable, at least until the animal is better 
known, for mere exterior resemblance does not necessarily imply an absolute 
affinity with that of Zrochus. : 
1b. Torinia, Gray, 1840; the shell does not differ from that of Solarium, 
but the operculum is conically elevated and composed of numerous volutions. 
Although there is no particular difficulty felt in accommodating the compar- 
atively few living species to these three divisions, it is really impossible to do the 
same with the fossil shells, and we can only very cautiously apply such a division 
to them. TZorinia was dismembered from Solariwm upon the examination of not 
more than two or three species with the animals and the opercula, and, it is 
possible, that many other similar variations of the opercula may be found among 
those species, to which the name Solarium has been restricted. Deshayes (loc. cit., 
p- 664,) arranges the eocene Solaria of the Paris basin in four sub-generic divisions : 
Solarium, Lamck., as restricted; Torinia, Gray; Disculus, Desh.; Philippia, 
Gray. I do not think, however, that any of these divisions can aid very much 
in the determination of the shells only. The Solarium disculus, Desh., which is 
apparently considered as the type of the section Disculus, would seem rather to 
agree with Philippia ; and again species, like Sol. gratum or Sol. discretum, Desh., 
referred to the section Philippia, do not correspond at all with that genus, as 
proposed by Gray, but rather with Zorinia. Any one after comparing the large 
number of specimens of our Solarium Coothoorense, would soon be at a loss, what 
to call a Torinia and what a Solarium ; and again in examining a similar number 
of Solarium Olapaudiense the same difficulty arises as regards Disculus and Phi- 
lippia. It is evident, that we have not yet discovered the proper characters of 
distinction, but it is still possible, that it may result from the study of the recent 
shells, and then be made of better practicla use in our paleontological researches. 
3Q 
