CHAP. II.] THE NOTOG/EIC REALM : ITS CHARACTER. 29 



where a very scanty and often peculiar fauna must be affiliated to 

 the general Australian type." To the north-east the line of de- 

 marcation of the realm from the Oriental region of Arctogsea has 

 been finally fixed at the deep channel separating the islands of 

 Celebes and Lombok on the one side from those of Borneo and 

 Bali (at the extremity of Java) on the other ; this division being 

 now well known under the name of " Wallace's line." 



All writers are, however, by no means agreed as to the right of 

 the whole of the area thus indicated to form a single zoological 

 division. Before the publication of Dr Wallace's great work, 

 Professor Huxley had proposed to separate New Zealand as a 

 region of equal rank with his Australasian region. At a later date 

 Professor Heilprin 1 suggested that the Australian realm should 

 include only Australia, Tasmania, New Guinea, with the smaller 

 Papuan islands, and New Zealand ; Polynesia, including all the 

 islands lying to the east of the Coral Sea, being raised to the rank 

 of a distinct realm (the Polynesian), while the Austro-Malayan 

 islands were regarded as forming a transitional tract between the 

 Australian realm and what is here termed the Oriental region. In 

 this connection it may be well to notice that the Austro-Malayan 

 sub-region of Dr Wallace is by no means coterminous with the 

 Austro-Malayan transition-tract of Heilprin, the former including, 

 and the latter excluding New Guinea. 



So far as mammals alone are concerned, Notogaea is widely 

 separated from the whole of the rest of the world by being the sole 

 habitat (both now and in the past) of the typical diprotodont 

 marsupials and the monotremes; although it must not be sup- 

 posed that either of these groups is distributed over the entire 

 area. As a matter of fact, apart from introduced rodents, 

 Polynesia is devoid of mammalian life with the exception of bats 

 and a rat 2 , while New Zealand has but two representatives of the 

 former group, and a rat which may or may not be indigenous. 

 But wherever we meet with a fully developed mammalian fauna, 

 as in the transitional Austro-Malayan islands, there a certain 

 number of marsupials are met with, although the monotremes 



1 Appendix, No. 17. 



2 Mus exulans, see Proc. Zool. Soc. 1895, p. 338. 



