324 



VERTEBRATE ANIMALS. 



American Opossums (pidelphidce), may be mentioned. The Bandi- 

 coots are little, rabbit-like Australian animals, whicli live upon 

 insects, and seem to fill the place held in the Old World by the 

 Hedgehogs and the Shrew-mice. The species of Dasyurus, though 

 of small size, are very ferocious ; and the Thylacine grows to the 

 size of a shepherd's dog, and is quite capable of destroying animals 

 as big as sheep. About twenty species of Diddphidce are known, 

 and they are all exclusively confined to the American continent. 

 They are all of small size, have pi-ehensile tails, and mostly live 

 among trees. The best-known species is the Virginian Opossum 

 {Didelphys Virginiana). Another species of Opossum, the Didelphys 

 dordgera (fig. 229), carries its young about on its back, the young 

 clinging to the mother by twining their prehensile tails round hers. 



Order III. Edentata or Bruta. 



This order of Placental Mammals comprises the Ant-eaters, Arma- 

 dillos, and Sloths, and is characterised by the fact that the teeth are 

 not covered with enamel, have no complete roots, and are never re- 



Fig, 230.— A, Side-view of the skull of Bradypus cvffiiUiger; B, Side-view of the skull 

 of Dasypus gigas. (After Giehel.) 



placed by a second set. As a rule, the teeth (fig. 230) are simple 

 cylinders, placed at a little distance from each other. Further, in 

 none of the Edentutrs are there any central incisor teeth, and in all 



