CHAP. XIII 



BACKBONED ANIMALS 



293 



to fend for themselves. In Australia the Marsupials 

 have been saved by insulation from stronger mammals, 

 which seem to have exterminated them in most other 

 parts of the earth, for the fossils show that the race had 

 once a much wider distribution. In their Australian 

 retreat, apart from all higher Mammalia (mice, rabbits, 

 and the like being modern imports), the Marsupials have 

 evolved along many lines, prophetic of the higher orders 

 of mammals. There are " carnivores " like the Thylacine 

 and the Dasyure, " herbivores ' like the Kangaroos, 

 " insectivores ' like the banded ant-eater Myrmecobius, 



FIG. 97. Phenacodus primaevus, A PRIMITIVE EXTINCT UNGULATE FROM 

 THE LOWER EOCENE OF NORTH AMERICA. 



The actual size of the slab of rock on which it rested was 49 inches 



in length. 



(From Chambers's Encyclop. ; after Cope.) 



" rodents ' like the Wombat, and the quaint " mole- 

 like ' Notoryctes. 



(3) In all the other orders of mammals there is a 

 placental connection between mother and unborn off- 

 spring. 



Distinctly separate from all the others are the Edentates 

 (probably several orders), represented by sloths, ant- 

 eaters, armadillos, pangolins, and the aard-vark ; and 

 the Sirenia or Sea-cows which now include only the 

 dua on g and the manatee. 



o o 



Along one fairly definite line we may rank three other 

 orders the Insectivores, the Bats, and the Carnivores. 



