BY ROBERT HALL. ^jc 



To strengthen that opinion, I have tabulated the 

 whole of the Australian birds, and find the same com- 

 parison is equally strong with every area (4). 



From the Papuan sub-region almost the whole of the 

 present bird fauna appear to have had their origin. 



Approximately 200 species of the 350 species of area 

 2 gradually emigrated from area 2 into area i, while 170 

 species of the 250 of area i gradually emigrated into area 



8, and gave it the greater part of its present avifauna. A 

 census of the avifauna of Northern Australia shows that 

 the greater part of the areas 2, i, 8 is the same with regard 

 to species, being numerically the strongest in species and 

 genera in area 2, getting less in number as we travel from 

 the Gulf country to the Fitzroy River country (area 8). 

 That is the positive evidence. The negative is seen in 

 the comparisons of the area 2 with 3 and 4, i with 7, 

 8 with 9. 



In comparing areas 8 and 9 (i) I find area 8 has ap- 

 proximately 200 species, and area 9 also has 200 species. 

 Common to both are 100 species, leaving 100 species in 

 8 and 100 species in 9 that do not encroach on each 

 other's territory. The distribution of the species of this 

 census shows that the 100 species of 8 are derived from 

 I, and the 100 species of 9 are mostly derived from 6 and 

 7. The reason surely lies with the desert between 8 and 



9, and the desert of area 7, acting as a barrier to expan- 

 sion. This does not exclude the migration of species be- 

 tween 8 and 9, which are a part of the 100 species common 

 to both. 



Area 8 is conspicuously made up of the genera of the 

 north, derived from area 2, while area 9 is as prominently 

 composed of the genera of the south, derived from area 

 6 and 4. This is exemplified in the Ploceidae of the north 

 and in Neophema of the south. 



Both areas 8 and 9 have scarcely any genera not re- 

 presented in 2 and 4 respectively, while numerically they 

 are very much weaker through the wave of emigration 

 decreasing as it went westward. 



(4) The distribution of the genera and species is where they 

 more commonly occur, and certainly not as "accidentals;" 

 further, sub-species recorded as such, and certain sub-species 

 recently recorded as species, are mostly not included in the 

 Tables. Gregory Mathews' Hand List has been referred to. 



(i) See Table III. 



