536 DEVELOPMENT OF THE N.O. MYRTACEjE, 



of Myrtaceae became thereby much contracted. In certain countries, 

 such as Australia and America, which, about that time, became 

 partially or wholly isolated from other tropical regions, the Myr- 

 taceae underwent divergent transformations, the Eugenias, Myrtles, 

 Campomanesias, Myrcias, Psidiums, Calyptranthes, and other 

 types marking a deployment of genera in the fertile tropics, the 

 capsular-fruited Myrtaceae marking an adaptation to less genial 

 conditions, while the Chamaelaucieae mark an organic response to 

 severer conditions of climate, and to a greater poverty and porosity 

 of soil, than the majority of the Leptospermeae. 



Geography. — The Cretaceous, in Australia, as in the greater 

 part of the world, appears to have been a period at once of genial 

 and moist climate, of reduction of the continental surface to low- 

 lying plains by stream-action, and a period also of great sea-trans- 

 gressions over the continent. The continent appears to have been 

 connected with Asia, at least throughout the lower Cretaceous, and 

 to have been separated therefrom at some period during the Upper 

 Cretaceous. 



New Zealand appears to have been connected with Australia or 

 New Guinea by way of New Caledonia in the Cretaceous, and the 

 first separation from the main Australo-Asiatic block appears to 

 have been that of New Zealand*, then the Australian province 

 appears to have been separated from Asia and its continuation 

 south and east to Celebes and Borneo. New Caledonia and Fiji 

 appear to have been separated later from the main mass, and 

 Celebes became separated from both Asia and Australia. Timor 

 and other Islands were separated from the continent at a later 

 date. 



In the Upper Cretaceous, the Australian Continent was occupied 

 by a central sea. By analogy with a study of Northern American, 

 Asiatic, and European conditions in the Upper Cretaceous, it 

 would be reasonable to infer that the Cretaceous sea completely 

 separated Western from Eastern Australia. There is no direct 



* See also C. Hedley, "A Zoogeographic Scheme for the Mid-Pacific." 



