﻿rO ALLEN S NATURALISTS LIBRARY. 



intimately connected with one another that any such sub- 

 division is impracticable ; and the most that can be done in 

 this way is to divide the Order Marsupialia into two Sub-orders, 

 mainly distinguished from one another by the form and struc- 

 ture of their teeth. It is true, indeed, that the more typical 

 representatives of these two groups also differ from one another 

 in regard to the structure of the hind foot ; but there is one 

 family which is intermediate in this respect, and thus shows 

 how close is the relationship of the two groups. 



As already mentioned, the Marsupials have adapted them- 

 selves to almost all modes of life, some running in the ordinary 

 manner, some progressing on the ground by long leaps, others 

 being arboreal, and others volant, after the manner of the 

 Flying Squirrels, while a single species has taken to a subter- 

 ranean Mole-like life. It is, however, very remarkable that not 

 a single Australian representative of the Order is aquatic in its 

 habits, so that such an animal as a " Marsupial-Otter" does not 

 exist in that region. The place in nature thus left vacant by the 

 Marsupials has been seized upon by the Duck-bill and by two 

 members of the Rodent order (otherwise so poorly represented 

 in Australia), of which the best-known is commonly termed the 

 Beaver-Rat {Hydroxys chfysogaster). In South America one 

 of the Opossums — the Water-Opossum — has, however, assumed 

 aquatic habits, having webbed feet, and passing most of its 

 time in the waters of rivers and streams. 



Except for their skins, some of which are imported in large 

 numbers to Europe, where they have a considerable value, the 

 Marsupials are of little commercial importance to man. None 

 of the herbivorous species have been domesticated as a source 

 of food-supply, their flesh being apparently but seldom eaten 

 at all ; while all the larger carnivorous kinds are killed off as 

 pests whenever met with, one or two having indeed been well- 

 nigh exterminated in many districts. 



