LXXVI PRESIDENTIAL ADDRESS. 



At a subsequent period the large Austral Continent became 

 divided into two parts — (1) a northern, consisting of the present 

 Papua and adijacent islands; and (2) a southern, including the 

 present Australia and Tasmania. During early Pleistocene times 

 there was probably a considerable extension eastwards of the 

 coast line of Australia, as compared with what obtains 'at present, 

 affording a more or less easy transit along this side of the Con- 

 tinent to its most southern part, which later became separated off 

 by the formation of Bass Strait. 



So far as Australia is concerned, it appears that during at 

 least a considerable part of early Pleistocene times, when the 

 ancestors of the present aborigines were spreading over the Con- 

 tinent, conditions were much more favorable than at present. At 

 that time, great rivers represented now by the Barcoo, Warburton, 

 and Finke, flowed down from the highlands of Queensland, New 

 South Wales and Central Australia, anid emptied their waters 

 into the Southern Ocean by way of what are now the drowned 

 valleys of Spencer and Vincent gulfs. These river courses, 

 together with that of the Murray, determined the line of migra- 

 tion of the early aborigines on the eastern and central areas of the 

 Continent. Later on there was developed the sag that resulted 

 in the formation of the present depression centering in Lake Eyre, 

 and the consequent shutting off of the communication of the great 

 central rivers from the Southern Sea. The rivers, save the 

 Murray, now flowed inland and with increasing desiccation, the 

 central area of the Continent, to a large extent, separated, 

 climatically, West from East Australia. So far as Tasmania is 

 concerned, it appears to have been separated from, and re-united 

 with, the main land more than once, the last union probably being 

 in early Pleistocene times, a subsequent sinking of the land trans- 

 forming the south-western corner of the old Continent into the 

 Island of Tasmania. 



From the biological point of view, the evidence is quite con- 

 clusive in regard to the early separation of Australia from 

 Eurasia. Apart from bats or insects that can fly or be oarried 

 by winds across stretches of water, mice and rats, that can be 

 carried in boats and drifting logs, Australia has received no immi- 

 grants by land from Eurasia since the Cretaceous period. She 

 received the ancestors of her very distinctive marsupial fauna 

 from the ancient American continent, most probably by way of 

 Antarctica, Avhen what is now Tasmania was still a part of the 

 Continent. The^ lung fish, Ceratodus, and the Monotremes, 

 Echidna and Platyj)us, and such lower forms as Peripatus, are 

 relics of a luore ancient fauna once widely distributed, but her 

 characteristic marsupials came at a later date, and the most 

 specialized of them, the Diprotodonts — kangaroos, native bears, 



