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OF SOUTHERN INDIA. 245 
XXVIII. Fumily,—ONUSTID Zi. 
H. and A. Adams’ Genera I, p. 361; idem Chenu; Puoripm, Gray ; XENOPHORID, Deshayes. 
The question as to the place of this family in the system is by no means settled 
with the last decision of Deshayes (Anm. s. vertb. foss. bas. de Paris, 2me. ed., 
Vol. II, p. 958, etc.). Palaontologists were accustomed to look for Xenophora in 
the neighbourhood of Zrochus, as long as they knew only a few fossil shells. This 
idea was introduced chiefly through D’Orbigny’s ‘ Paléontologie frangaise’, and was 
supported by the descriptions of several very characteristic Onvsripa under the name 
of Trochus. Since the animals have been made known, and a little more attention 
paid to the formation of the shells, this classification next to Trochus has become 
the most improbable of all. I shall follow here H. and A. Adams, who place the 
family after the Szziqvarupm, although I confess, that I am not in a position 
to give a sufficient reason for this arrangement. It is not easy to reconcile oneself 
to the place, which I have assigned to either of the two last-named families. 
Of Gray’s classification of the Pzorrip# (= Ovusrip2), next to the Srromerpsz 
(= Axara), Mr. Deshayes simply says, that it is inadmissible. It may be so, but 
the proof has not yet been given.—We have not accepted Gray’s classification of 
the two last named families as a higher division under the name of Lepropopa, 
simply because we have no materials to prove it, but we do not wish in the least to 
pronounce its non-admissibility, or even a great improbability of its correctness. We 
have, when speaking at length of the family Azara, repeatedly drawn attention to 
the great variety of shells which it includes, and to the probable changes which 
may be expected in the classification of them. 
When we compare the animals of the 4za4ra4 and those of the Onusripz, there 
is certainly nothing to be said against their close relationship. Of course we must 
not take two extremely different species, but single organs, as they are subject to 
variation within the family; for instance, the foot of Zerebellum, the tentacles and 
eyes of Aporrhais, the loug rostrum and slightly expanded mantle ef Struthiolaria, 
and others. The operculum of Xenophora is by no means so very differently built 
from the strong and lamellar form of that of many species of Strombus ; the only 
difference seems to consist in its position in the aperture, for the somewhat more 
triangular shape cannot certainly be considered as a distinction of very great 
importance. I would only in conclusion call attention to those species of the 
Onusrip#, which have a very largely expanded outer lip, to which we scarcely know 
anything similar, if we ignore its relation to similar expansions in the Azara. 
The great obstacle, which exists to admitting Gray’s introduction of the division 
LEptToroDA, is, of course, the old classification of the SrpHoNostoMATA and Hotos- 
ToMATA, but, although we have retained this ourselves from want of a better one, 
we have already repeatedly observed, that it cannot remain permanently, and must 
be replaced by some other. When that has been successfully done, the division 
Lepropopa of Gray will very probably receive more attention. 
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