OF SOUTHERN INDIA. 187 
end of the SrpHonostoMATA, so long as this tribe of Mollusca is retained with 
any regard to systematic value. We cannot perceive for what reason such distinct- 
ly canaliculated shells ought to be summarily transferred to the Honostomara, 
and it seems to us that this error has been habitually introduced by a mistaken identi- 
fication of the former tribe with the signification of zoopHaca, and that of the latter 
with the pHyToPHAGA. If this latter classification be adopted, there must be several 
and very considerable changes effected in the arrangement as proposed at the 
present, There is not, however, very much importance to be attached to either of 
these divisions. 
H. and A. Adams proposed two sub-families, crrrrmmv and poramipin&, the 
latter of which would form a transition to the Mezanzrp%. It is usually stated, 
that this proposition was made on account of the paucispiral and oval, or multispiral 
and circular form of the operculum alone, but the mode of living of the species in 
both these divisions and the differences of the structure dependent upon it are far 
more important, the first being marine, the latter brackish or fluviatile inhabitants. 
The shells of the poraurpin# exhibit consequently many minor differences in 
their structure, they have generally a shorter and less deeply channelled anterior 
termination, a thick epidermis, etc. We fully concur with many conchologists in 
the desirability of keeping up this distinction into two or perhaps, according to 
Gray, into three families, adding the rrzxorm. Instead of obliterating those 
results, which have been obtained after much tedious work, it would be more appro- 
priate to seek first for new facts, and to see whether these divisions could be 
made more practicable for the paleeontologist. The same might be said with regard 
to the genera and sub-genera, which have been established by different authors. We 
restrict our remarks chiefly to the marine forms only. Itis true that, so long as 
we are not in the possession of well preserved fossil materials, paleontologists 
will adhere for many years to a general name, such as Cerithiwm, but that mere 
name cannot continue to comprise all the great variety of forms. 
a. Sub-family—CERITHIINZ (Cerithium, auctorun). 
There is not much known of paleeozoic forms of the crrrrayv, but the oldest 
secondary species exhibit a remarkably close relationship to Nerinea of the 
PyraupeELtin#. For a number of these old Cerithia Piette proposed the name 
1. Fibula, 1857 (Bull. Soc. Géol. France, Vol. XIV, p. 556). The shells 
are turreted, of moderate thickness, smooth or with short semi-obsolete transverse 
ribbings, a short canal, and contorted columella. The triassic species described and 
figured by Stoppani as doubtful Nerinee (see Pal. Lomb. 1 ser. Pl. VII and VIII) 
or the Cerithiwm Esinense of the same author (ibid, Pl. XV, Fig. 11), are among others 
the oldest representatives of this genus. Piette notes several jurassic species from 
the ‘Bathonien’ of the Ardennes department, and others are known from the 
German and English Jura. In the more recent deposits these forms are much more 
rarely to be met with, although we know little as yet about the true character of cre- 
taceous species, like Cer. excavatum (Pict. et Roux; Grés verts, Pl. XX VII, Fig. 7) 
