BY ROBERT HALL. ojy 



Between areas 4 and 5 we have a water barrier. As 

 Tasmania is considered to tiave been connected with 

 Victoria in post-glacial times, it would appear as if such 

 forms as Menura, Psophodes, and Sphenura would not 

 enter the higher latitudes when they had the opportunity. 

 This is so with a large portion of the birds of area 4. If 

 they then existed in area 4, surely a larger proportion, 

 including Menura, should be showing in area 5. Pos- 

 sibly Menura got further south, in area 4, as Sarcophilus 

 and Thylacinus died out, and was not far enough south 

 when the subsidence of Bass Strait occurred. 



At the southernmost end (area 5) of this eastern 

 course of emigration there are known to us only two 

 genera peculiar to it, and one of them ill-defined (Acan- 

 thornis). Its close allies (Acanthiza and Sericornis) (i) 

 are of a family that has mostly evolved its numerous 

 species in Southern Australia, these two genera being 

 scarcely represented in areas 2, i, 8, though represented 

 in New Guinea. 



The western line of emigration, beginning at area 4 

 and continuing through 6 to 9, is one of much interest. 



Area 9 has derived its avifauna from areas 7 and 6. 

 Area 6 has derived a large portion from area 4. Area 7, 

 adjacent to 6, has locally evolved a part of its species, and 

 sent a portion of it to area 6. 



Thus area 6 is larger in number of species than area 

 4, pointing to the favourable conditions for species mak- 

 ing by the already mentioned waterways of the Eyrean 

 sub-region. 



That area 7 appears to derive its genera and most of 

 its species from areas 3 and 6 may be deduced from the 

 data of geographical distribution in the faunal sub- 

 regions. 



An examination of these data will show that it is, least 

 of all, in harmony with the areas 8 and i. It is not easy 

 to prove that area 7 was not populated by immigrants 

 from area 2, but it is easier to attempt to prove that it w^as 

 in the greater part populated from areas 4 and 6. 



(i) Strangely enough the two closest offshoots of Sericornis 

 in Australia are at the opposite poles of its eastern range, viz., 

 Oreoscopus in area 2 and Acanthornis in area 5. A comparison 

 of the pterylosis of these three genera would be interesting. 



