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. 



