THE NATURALIST IN AUSTRALIA. l6l 



some idea of what happened to the Australian Continent during; 

 the Cretaceous period. As will be seen by the accompanying 

 map, it would now appear as two islands one, an extensive 



I. 



A. WESTEEN ISLAND, DATING FROM THE SILURIAN PERIOD. 



B. TRACT OF LAND SUBMERGED DURING THE CRETACEOUS AND EARLY 



TERTIARY PERIODS. 



C. EASTERN ISLAND OR CHAIN OF ISLANDS. This Region has under- 



gone changes of elevation and has been the scene of much 

 volcauite activity at various periods. 



(Adapted from Wallace's " Island Life.") 



table-land, on the west, with its undisturbed original population 

 of plants and animals, whilst over against it, on the east of a 

 shallow sea, there stretched a lofty ridge of materials chiefly 



