666 president's address. 



Another intoresting point is strongly brought out. Central 

 Australia furnishes the most striking Australian instance known 

 of the " potency of climate compared with the inefficiency of 

 physical barriers " in regulating geographical distribution. In 

 an interesting address " On the Geographic Distribution of Life 

 in North America," by Dr. Merriam, this author points out that 

 Wallace* greatly underrates the importance of temperature as a 

 factor in determining the distribution of animal life; and he adds : 

 — "It is now pretty generally conceded that temperature and 

 humidity are the chief factors governing the distribution of life, 

 and that temperature is more potent than humidity." Australia 

 is a continental tract, completely isolated, not reaching into very 

 high or very low latitudes, without mountain ranges sufficiently 

 high to reach the snow line, and its shores are washed wholly by 

 tropical or temperate seas. It would seem that Merriam's 

 dictum will not apply to the Eremian Region. In his important 

 Presidential Address at the Sydney Meeting of the Australian 

 Association for the Advancement of Science, Professor Tate 

 said : — " The chief factors influencing the geographic dis- 

 tribution of plants are those of temperature and moisture, 

 because they are indispensable; of the two, so far as Australia is 

 concerned, the latter is by very far the more important." This 

 generalization is now shown to apply equally well to animal life. 



Finally, the Report furnishes confirmatory evidence as to the 

 past history of Central Australia, as previously sketched by Prof. 

 Tate and others. The elevated portions of the Larapintine 

 region have continued to be land-surfaces since pre- Cretaceous 

 times. They were insular members of the Archipelago whose 

 shores were washed by the Lower Cretaceous Sea during the 

 period of deposition of the Rolling Downs formation. During 

 the deposition of the Desert Sandstone formation in Upper 

 Cretaceous times they remained to some extent in the condition 

 of islands, but the marine conditions had given place to a lacus- 

 trine order of things. With a favourable climate and abundant 



* Proc. Biol. Soc. Wash. vii. (1892). 



