116 AUSTRALIAN SUB-REGIONS. [CH. II 



with green, a protective colour in the forests which they 

 inhabit. Mr Wallace, to whom the above suggestions in 

 explanation of the great prevalence of Pigeons are due, 

 estimates that " three-fourths of the genera have repre- 

 sentatives in the Australian region, while two-fifths of 

 the whole are confined to it." 



The Australian region is not quite so destitute of 

 Mammals not belonging to the orders Monotremata and 

 Marsupialia as is sometimes apt to be inferred. Apart 

 from the peculiar genera of Rodents and the few other 

 peculiar forms enumerated in the above table, a Macaque 

 and a Cynopithecus get into the region where it touches 

 the Oriental ; the remarkable Oriental Lemur the Tarsius 

 also enters the region ; Viverridse and shrews are not 

 unknown, though few and rare ; the genus Sus extends as 

 far into the region as New Guinea. On the whole this 

 is perhaps the most isolated in its affinities of all the 

 regions. The boundary between it and the Oriental is 

 sharply marked ; I have dealt elsewhere (see below) with 

 such resemblances as it affords to other parts of the world 

 and the Neotropical region. 



The Australian has four well marked sub-regions, viz., 

 (I) Austro-Malayan, (II) Polynesian, (III) Australian, and 

 (IV) Novo-Zealanian. 



I. The Papuan or Austro-Malayan sub-region in- 

 cludes not only New Guinea and all the islands lying to 

 the west of it as far as the commencement of the Oriental 

 region, but the extreme north of the continent of Aus- 

 tralia. Being entirely, or nearly entirely, made up of 

 islands it has a large number of peculiar forms. The 



