OF THE MARSUPIALIA,. 331 
lets. This generalization is, however, less cogent in the present question than the pre- 
ceding, because the same modification, as regards the separate entry of the vene cave 
superiores, obtains in a few placental species, as the Klephant and some of the Rodentia. 
But the cardiac characters, of which one is common and peculiar to the implacental 
quadrupeds, and the other, while it is universal in them, occurs only as an exceptional 
condition in the placental series, cannot be rejected in a philosophical consideration of 
the affinities of the Marsupialia. 
Several peculiarities of the osseous system, besides the well-known one of the ossa 
marsupialia, and unconnected with the generative peculiarities, will be pointed out in the 
subsequent essay on the osteology of the Marsupialia. And while on the present ques- 
tion I may observe, that had the Sarcophagous Marsupials of the present system been 
subjected to the scrutiny of the myologist as members of the ordinary group of Fere, 
he must have noted them as presenting a very remarkable modification of the muscles 
of the hind leg ; for whereas in all the placental Fere the flecor longus digitorum pedis 
sends tendons to the toes, as its name implies; in the Dasyures and Phascogales it 
is inserted fleshy into the fibula, and the knee- and ancle-joints are so modified as, 
through the action of the muscle so inserted, to admit of rotatory movements of the 
hind foot analogous to the pronation and supination which in the placental quadrupeds 
are peculiar to the fore-feet. But the myologist would have been still more surprised 
if in dissecting the Opossums and Phalangers, when associated with the Monkeys and 
Lemurs in such a group as Illiger’s ‘ Daumenfiisser’ (Pollicata), characterized by hinder 
hands, he should have found precisely the same modification of the flecor longus digito- 
rum—the same conversion of that muscle, by corresponding modifications of the knee- 
and ancle-joints, into a rotator of the hind-leg ; and that notwithstanding the difference 
in the general structure and powers of the hind foot in the ferine or falculate and the 
pollicate orders, the marsupial species should have differed in both groups from the pla- 
cental ones by precisely the same singular modification. And if now the myologist were 
to proceed to compare the Wombat with the Beaver or any other placental Rodent, and 
were to discover here also precisely the same difference in the muscles and motions of 
the hind legs, he could hardly avoid suspecting that some closer affinity must subsist 
between the species enjoying the common properties of rotation of the hind foot than 
was indicated by the’classification under which I have supposed them to have been pre- 
sented to his notice. It is, in fact, only in those Marsupials in which the offices of sup- 
port and locomotion are devolved exclusively or in great part upon the hind-legs, as in 
the Kangaroos, Potoroos, and Perameles, that the hind-feet are strengthened at the ex- 
pense of the loss of the movements of rotation. 
Finally, I may observe, that in the dental system itself, the varieties of which have 
been chiefly appealed to as sanctioning the dispartition of the Marsupial order, we find 
an important peculiarity, by which the carnivorous, omnivorous, and strictly vegetable- 
feeding genera alike agree with each other, and differ from the corresponding placental 
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