32 THE GEOGRAPHY OF MAMMALS 



Bettongia and its allied genus Potorows embrace the 

 Kangaroo-rats, as they are often termed. These are all 

 small, never exceeding a rabbit in size ; they possess well- 

 developed canine teeth, and have the central toes of 

 the fore feet elongated to accommodate their digging 

 habits. 



Having completed our survey of the Monotremes and 

 Marsupials of the Australian Sub-region, we must now con- 

 sider the Eutherian series, which, as has been already 

 shown, plays a very subordinate part in this extraordinary 

 fauna. Putting aside the marine mammals — the Seals, 

 Cetaceans, and Sirenians — and confining our attention to 

 the terrestrial groups, we find only three of the usually 

 recognised orders, namely, the Rodents, Bats, and Carnivores, 

 with any representatives in this strange country. And the 

 Carnivores would be perhaps better considered as quite 

 external to the fauna of Australia proper, since the solitary 

 member of this group found within its limits is the semi- 

 domesticated Dingo, which, as already suggested, has not 

 improbably been introduced by the primitive native 

 inhabitants. 



Monkeys, Insectivores, and the most useful Order of 

 Ungulates, to which its grassy plains would appear to be, 

 and, as we know by actual experience are, excellently 

 adapted, are alike unknown, except as introductions, in 

 Australia, and their functions in a state of nature seem to 

 be performed by the various groups of Marsupials. 



Of the other orders, the Rodents are represented by six 

 genera, all belonging to the Mice (Muridze). Of these four 

 are confined to Australia proper, while two others also 

 occur in the Papuan Sub-region; the remaining one, the 



