136 NATURE STUDIES. 



the kangaroos, wombats, phalangers, &c. in a word, 

 the whole of the native population of Australia (along 

 with the New World opossums), forming the order of 

 Marsupial-id, or that of the "pouched" quadrupeds. 

 In Fig. 7 is represented the pelvis or haunch-bones of 

 a kangaroo. At a, a, the marsupial bones, or those 

 supporting the well-known pouch, are seen. These 

 bones are only found in the Marsupials and Mono- 



Fig. 7. Haunch-bones of Kangaroo : a, a, marsupial bones ; 

 d, socket for thigh-bone. 



tremes, and whilst in most of the former they support 

 a pouch, they are never associated with that structure 

 in the Mono tremes. 



Now, it is in the Monotremes represented by the 

 Ornithorhynchus (Fig. 6) and the Echidnas that the 

 characters linking quadruped life to lower life are 

 most typically seen. It may be well to strengthen 

 our position at the outset, by reminding the reader that 



