VERTEBRATA. 
343 
mouths by special muscles. 176 They have “ marsupial 
bones” projecting from the pelvis, which may serve to 
support the pouch; but as the Monotremes have the same 
bones, but no pouch, they doubtless have some other func¬ 
tion. These bones are peculiar to animals having no pla¬ 
centa, namely, to Monotremes and Marsupials. The brains 
of Marsupials resemble those of the Monotremes, except 
that the cerebrum of the Kangaroo covers the olfactory 
lobes. All have the four kinds of teeth, and all are cov¬ 
ered with fur, never with spines or scales. Except the 
Opossums of America, all are restricted to Australia and 
Fig. 332.—Virginian Opossum (Didelphys Virginiana). 
adjacent islands. The Marsupials are almost the only 
Mammals of Australia, a few species of Rodents and Bats 
being the only placental Mammals. The Marsupials have 
here developed into forms corresponding in their habits 
to the orders of placental Mammals in the rest of the 
world. The Kangaroos take the place of the large her¬ 
bivores— the Ungulates. The Thylacinus and Dasyurus 
are the marsupial carnivora. Other forms are squirrel¬ 
like in shape and habits, and still others are insectivorous. 
