be 
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SOME NEW AND RARE CEPHALOPODA. 125 
the rank of an equivalent section, under the name Libera. The primary division of 
Cephalopods, proposed by M. Deshayes'’, into the two orders Octopodes and Decapodes, is 
essentially the same as that of M. De Haan, as the latter group combines the naked 
or dibranchiate species with the Nautilacea of De Blainville. 
Thus it will be seen that most of the preceding schemes are based on the modifications 
of the shell or its analogue, and some of them, as that proposed by M. Férussac, have 
been published since the modifications of structure in those Cephalopods which inhabit an 
external chambered shell have been pointed out. It is this circumstance which has 
chiefly induced me to state here my views of the distribution of the Cephalopods, founded 
in part on the dissection of the Nautilus Pompilius, and on a comparison of its organ- 
ization with that of the Cephalopods with internal shells, so far as indications of their 
structure can be obtained from the hitherto imperfect descriptions of the recent Spirula, 
and from the remains of the Belemnites. But before I proceed to detail these views I 
shall briefly adduce the few examples of the classification of the Cephalopods, in which 
an attempt is made to distribute these highly organized Mollusks into groups founded 
on considerations of structure of higher importance than tegumentary or testaceous 
characters. 
The first classification of this nature is due, as might have been expected, to a highly 
accomplished classical Naturalist, well versed in the zoological writings of Aristotle. 
This Naturalist, Schneider, to whom we owe the best translation of the ‘ Historia Ani- 
malium,’ is the first of the moderns who attempted to revive the philosophical views 
which guided the Father of Natural History in his distribution of the Mualakia or Cephalo- 
pods. For this group of Cephalopods Schneider proposed the name of Octopodia, compre- 
hending therein the species in which two superadded elongated slender arms are present, 
but which were distinguished by Aristotle from the ordinary eight arms, under the name 
of ‘ Proboscides.” Schneider* divides the class into two groups, which are characterized 
as follows :— 
1. Pedes octoni breves, promuscides bine, venter pinnatus, ossiculum dorsi. Ex. Sepia, 
Loligo, Teuthis, &c. 
2. Pedes octoni longi basi palmati, absque promuscidibus, pinnis et osse dorsali. Ex. Po- 
lypus, Moschites, Nautilus (or Argonauta) ; and indicates a third, founded on Rumphius’s 
description of the Nautilus Pompilius, with the following character : Pedibus lobatis, seu 
digitatis absque acetubulis. 
The classification proposed by Dr. Leach’, which in one respect is inferior to Schnei- 
der’s, is also essentially based on the modifications of the organs of locomotion. In this 
scheme Dr. Leach leaves entirely out of consideration the chambered shells, and appa- 
rently restricts the class Cephalopoda to the naked species. These he divides into two 
' Encyclopédie Méthod. 1830. 
® Sammlung Vermischter Abhandlungen der Zoologie, &c., 8vo. 1784. 
$ Zoological Miscellany, vol. iii. 1817. 
