330 THE DISTRIBUTION OP AUSTRALIAN LAND-BIRDS. 



In the distribution of the lairds under review there are 

 certain points of interest — 



(a) The genera and species are numerically strongest 



in areas 2 and .:^, those of area 2 not represented 

 in area 3 being northern or Papuan forms, while 

 those of area 3 not in area 2 being mostly 

 southern or central forms (probably evolved in 

 Australia), approximate 12 per cent, of the 

 whole in each case. 



That the list of the genera of either area 2 or 3 

 is 16 per cent, stronger than the genera of any 

 other area, while in species area 2 is approxi- 

 mately 20 per cent, stronger than area 3, and 33 

 per cent, stronger than area 7, the next in com- 

 parative strength. 



(b) The genera and species get less and less as they 



travel west from area 2 so far as the Fitzroy 

 River (area 8), and that they are mostly Papuan 

 forms, or closely allied to them (i). 



(c) The genera and species get less and less the 



further south they get from area 3, the tropical 

 forms rapidly deci^easing in number, and giving 

 place to many Australian-born genera and 

 species. 



(d) The desert barrier maintains a ditference between 



the Passerine genera and species of areas 8 and 

 9- 



(e) Area 7 derives its avifauna principally from areas 



3 and 6, while the birds of area 9 are derived 

 from areas 7 and 6. 



(f) Porphyrocephalus appears to be the only genus 



common to areas 8 and 9, and peculiar to them, 

 ; i.e., to the western third of the continent. There 



; \ are ,niany genera peculiar to the eastern third. 



(i) W. Vi Legge, " A.A.A.Sc, vol. x., p. 220, 1904," points out 

 that the avifkuna of the Northern Territory would be closer re- 

 lated to that of New Guinea if the physical features and vegeta- 

 tion were not so different. While Colonel Legge sees little 

 affinity betweein the birds of my areas 8 and i and those of New 

 Guinea, I am of opinion that their origin can be traced to New 

 Guinea and to area 7, rather than to Western Austro-Malayasia. 



