MARSUPIATA. 
16 
Mammalia. Such an interpretation cannot be made of these analogies, for in so 
doing we must admit that those groups of Marsupialia, which typify the orders 
Carnivora , Insectivora, Rodentia, &c., are groups of equal rank to the orders 
they typify, and if we carry our analogies further, we shall find that such a 
view will be by no means borne out. For instance, in the structure of the 
brain, there is so much difference between the placental Insectivora and the 
Carnivora , that many naturalists do not admit of these two sections being 
arranged near to each other, and by almost all who have recently treated of the 
classification of the Mammalia, the Insectivora and Carnivora are admitted to 
be distinct orders. Now if the order Carnivora is represented by Thylacimu 
and Dasyurus, and the order Insectivora by Phascogale , Perarneles , &c. 
almost the only point of distinction between the carnivorous and insectivorous 
marsupial groups consists in a slight difference in the structure of the teeth ! 1 
Geoffroy, who established the genus Dasyurus, regarded the type of TemmincVs 
genus Phascogale as a member of that genus; and Professor Owen, as well, I 
may say, as every mammalogist whose labours I am acquainted with, regard 
Phascogale and Dasyurus as members of the same family: how then can two 
species of the same family represent in rank two orders ? Again, upon a careful 
examination of the Wombat, I find so many points in common with the Phalanghti 
group—that it is so intimately related to the Koala (which is more clearly an 
aberrant Phalangista), as indicated by the structure of the stomach, and the 
deficiency in the number of the false molars, and the total absence of tail—that 
I am inclined to regard the genus Phascolomys as presenting an aberrant form 
only of the Phalangislid<v : that the thumb should be reduced to a small sire 
in this animal, which differs from others of its (supposed) family, in living upon 
the ground, I am prepared for, since in the Dasyuridce the same thing takes 
place under similar circumstances. I am also prepared to find in an herbivo¬ 
rous group like the Phalangistidc r a difference in the structure of the molar 
teeth in having them rooted in one case and rootless in another, for such 
happens in other herbivorous groups of Mammalia. Can I, then, regard the 
Wombat as constituting one order of Mammalia, and the Phalangers another, 
and at the same time suppose the one to represent the highest group of 
placental mammalia (Quadrumana) and the other the Rmlenlia, which is one 
of the lowest ? might we not regard the last-mentioned group CRodentiaj as 
a class, because the Sciurida; typified the Quadrumana , and the Murid*, in 
their comparatively carnivorous habits, represented the Carnivora, the Agoutis 
the Rummantia , and, lastly, because the Capibarn quite as strongly typified 
the Pachydermata as does the Wombat the Rodentia. The analogies are here 
In stating this, it must be observed, I am comparing Phascogale with the 
Dasyuri, in which I include Thylacinus. Perarneles differs much more from 
Phascogale than does that genus from Dasyurus. 
