104 ELEMENTS OF COMPARATIVE ZOOLOGY. 



pouch is supported by a pair of bones which extend forward 

 from the pelvis the marsupial bones, and these, as well as 

 a peculiar inbending of the angle of the lower jaw, serve at 

 once to distinguish any marsupial skeleton. Were these 

 the only characters to be considered we should not be war- 

 ranted in placing these forms in a subclass by themselves, 

 but there are other characters connected with reproduction 

 which justify this course. The living marsupials have a 

 peculiar distribution : they are restricted to warmer Amer- 

 ica and the chain of islands extending from Australia to 

 Celebes. Fossil forms are found in Europe as well. 



The American species are all opossums forms with pre- 

 hensile tails and have given rise to the expression 

 ' ( playing 'possum," from their habit of feigning death when 

 disturbed. Their food is chiefly insects, but birds, eggs, 

 etc., are not despised. 



Australia is the real home of the marsupials; indeed at 

 the time of its discovery this continental island contained 

 only marsupials, if we except the dingo, or native dog. 

 In this region are found forms which recall animals of 

 different groups occurring in other parts of the' world. 

 Thus the wombat resembles in size and teeth the beaver; 

 the thylacines in habits and in form are dog-like, while 

 the phalangers in size and appearance are like the flying 

 squirrels, and, like those animals, they have that same fold 

 of skin which enables them to glide through the air from 

 tree to tree. Most familiar of all the Australian forms are 

 the large grass-eating kangaroos, in which the fore legs 

 have become almost useless for locomotion, the animal 

 jumping with its hind legs, and when resting, supporting 

 itself upon these members and its enormously developed 

 tail. There are also fossil marsupials in Australia, some 

 of them of enormous size. Thus Thylacoleo was as large 



