166 MAMMALS OF THE PACIFIC WORLD 



are not stopped by impassable barriers or prevented by other 

 species. 



The zoological regions or subregions which are related to 

 the Pacific and East Indian area comprise parts of the cold 

 Palearctic or Eurasian (northeastern Asia) and Nearctic 

 (Alaska), a part of the warm Oriental (southeastern Asia), the 

 Australian (Australia, New Guinea, and the Solomon Islands), 

 and the Neotropical (limited to a few strays from Central and 

 South America). 



An important if anomalous area containing faunas of mixed 

 archaic and "modern" mammals lies between the tropical Ori- 

 ental and Australian Regions. This area, because its fauna 

 is chiefly Asiatic in origin and contains few animals derived 

 from Australia, can well be regarded as a subregion of the 

 Oriental region. It includes four principal island groups, each 

 of which is to some extent f aunistically distinct : the Philippines, 

 Celebes, the Moluccas, and the Lesser Sunda Islands. It has 

 been variously named the Indo-Australian Subregion, the 

 Australo-Oriental Subregion, and Wallacea, named for one of 

 its early explorers, Alfred Russell Wallace. New Guinea, with 

 the Solomon Islands, is held to be a subregion of the Australian 

 Region. 



The "subregions" of the open Pacific, the Polynesian, Micro- 

 nesian, and Melanesian Subregions, are ethnological rather than 

 biological conceptions. Their limited faunas are derived from 

 one or other of the biotic regions of the adjoining continents. 



FAUNAS OF THE PACIFIC ISLANDS 



Numerous different kinds of animals, as shown beyond in the 

 geographical index, inhabit the various groups of islands of the 

 Pacific. It has been pointed out that the ancestors of animals 

 living on islands came originally from the continents during the 

 course of an almost unimaginably long period of time. Those 

 continental sources, which have contributed very unequally to 



