166 BARBOUR: ZOOGEOGRAPHY. 



8. Apparently the Papuasian fauna, taken as a whole, is sufficiently well 

 differentiated to be considered as an entity almost as distinct as that which has 

 always been called the typically Austrahan fauna. This is shown by the con- 

 ditions seen amongst a number of groups of animals. There is also evidence of a 

 distinct fauna in western Dutch New Guinea, which may have been separated 

 from eastern Papua during part of the time that eastern Papua was one with 

 northern Queensland. 



9. The manifold origin of the fauna of Austraha seems worthy of emphasis. 

 That the cystignathids and hylids, among amphibians, came from South America 

 seems to be almost beyond contention; while other groups suggest an Asiatic 

 derivation. The assumption that in western Australia the many characteris- 

 tic Australian types were evolved while this region was separated from Queens- 

 land, and while the latter was in connection with New Guinea, seems to be the 

 only satisfactory explanation of the fact that there is so strong a Papuasian 

 element in the fauna of Queensland, and that so many of the autocthonous 

 Australian genera are absent from New Guinea. 



10. Broadly speaking, flotsam and jetsam methods of dispersal have played 

 a negligible part in providing any of the islands under discussion with the fauna 

 which they now support, although in some cases species carried by human 

 agency have circulated widely. 



11. There is evidence, though as yet it is of an unsatisfactory and frag- 

 mentary nature, that the species population of an island has a very direct rela- 

 tion with the surface area of that island, other things being equal. It would 

 not be possible, however, to compare in this way the faunas of two islands having 

 the same size if one of them had a heavy rainfall and luxm-iant vegetation, while 

 the other was arid. 



The evidence which would show that any existing island has remained un- 

 changed faunally since the time when it formed a part of the land-bridge between 

 Austraha (not Queensland) and continental Asia is apparently altogether wanting. 

 The geologic formation of Timor and Sandalwood (or Sumba Island) would lead 

 one to suppose that these islands might be the remains of an ancient synclinal 

 arc which curved from Austraha toward the mainland. The zoologic evidence 

 is unsatisfactory, although Timor supports a number of species which are in 

 marked contrast to those found throughout the Lesser Sunda Island chain. 



13. Neither Wallace's nor any other fine can be held to form a real zoo- 

 logical boundary. A transition zone with a fairly definite western frontier and 

 with an eastern frontier incapable of equaUy clear definition seems really to be 



