II.] AUSTRALIAN REGION. 31 



Although the northern half of Australia lies within the tropics, 

 yet few portions of this great island present that 

 luxuriance of vegetation which we are accustomed 

 to associate with tropical scenery ; and large tracts 

 of the interior, owing doubtless to the absence of elevated moun- 

 tain ranges in the central districts, form arid sandy deserts more or 

 less unsuited to the maintenance of animal life. The coast regions 

 and the borders of the larger rivers are accordingly those where 

 vegetation flourishes best ; the finest tracts of pasture-country, well 

 supplied with water, lying to the east and south-east, and Victoria 

 possessing a mountain range whose summits are perpetually 

 clothed with snow. Mountains also occur in the dry and hot 

 western districts. Although Tasmania enjoys moister conditions, 

 Australia as a whole is characterised by the lack of water and the 

 general dryness of its climate ; and it is probable that to this 

 aridity the number of jumping animals, such as kangaroos, rat- 

 kangaroos, and jerboa-rats, now characteristic of this part of the 

 region is due, since such creatures are admirably adapted for 

 traversing long distances in search of food and water. On the 

 other hand, New Guinea, together with the Papuan islands, has a 

 moist tropical climate, essentially different from that of Australia, 

 but similar to the conditions obtaining in a large portion of 

 the Austro- Malayan islands. Hence it is not to be wondered 

 at that the mammals of New Guinea differ very markedly 

 from those of Australia ; this being especially noticeable in the 

 paucity of typical jumping kangaroos, and the proportionately 

 large number of arboreal members of this group. Nevertheless the 

 mammalian fauna of Queensland and North Australia exhibits a 

 marked approximation to that of New Guinea, one species of 

 kangaroo, as well as a cuscus, a striped phalanger (DaJylopsila), a 

 flying phalanger (Petaurus), a pouched-mouse (Phascologale), and 

 an echidna, being common to the two areas, and it is in these 

 countries alone that tree-kangaroos are met with. From these 

 resemblances in their faunas and especially from the restriction 

 of the monotremes to these two areas, there can be no question 

 as to the propriety of including Australia and New Guinea in the 

 same zoological region, and thus separating the latter country from 

 the Austro-Malayan region. 



