280 SPENCER MOORE [october 



doubt whether Professor Tate does not estimate too highly the rainfall 

 of Central Australia during the Diprotodon period. The evidence 

 relied on by Professor Tate is, it will be remembered, of two kinds, 

 biological and physiographical. Now if the districts where Diprotodon 

 remains are found were to a considerable extent lacustrine, conditions 

 might well have prevailed there essentially similar to those occurring 

 now in Central and South-Eastern Brazil, where, during the dry season, 

 when the cerrado country is completely parched, a rich flora, maintained 

 by condensation of vapour during the early morning hours, flourishes 

 in the river-valleys. The remains, therefore, of large Herbivora by no 

 means prove that the whole country afforded subsistence to those 

 animals ; and although the existence of lakes warrants the conclusion 

 that the rainfall was greater than it is at present, there may still have 

 been many places adapted to xerophilous vegetation, and to that alone. 

 As regards the physiographical evidence, we have to take into calcula- 

 tion the probable effects of a great lowering of temperature, even if the 

 agency of ice cannot be invoked. Professor Tate and Mr. Watt, 1 after 

 a careful examination on the spot, deny the evidence of ice-action, 

 although to explain certain phenomena easily susceptible of such an 

 explanation, they are driven to resort to a theory they themselves 

 admit is " wild in the extreme." On the other hand, Professor Baldwin 

 Spencer and Mr. T. M. Byrne, 2 as the result of a recent investigation, 

 have no doubt of ice-action in Central Australia, though they decline 

 to say at what period it was in operation. But apart from this, we 

 have incontestable evidence for a cold climate in South Central 

 Australia during past Miocene times, when the southern part of South 

 Australia, as is well shown at Hallett's Cove, was glaciated. Now, 

 under these circumstances, much of the precipitation falling on Central 

 Australia would take the form of snow, which, during the summer 

 months, would melt and thus release large bodies of water sufficient 

 to cause a considerable amount of denudation. On the whole, there- 

 fore, we need not suppose that the rainfall of Central Australia during 

 the period under review, although doubtless greater than at present, 

 was so excessive as to prevent xerophilous vegetation flourishing side 

 by side with hygrophilous, and contrasting Central Australia with 

 Europe there is reason for supposing that while in the latter case 

 conditions favouring a mixed xerophilous and hygrophilous flora were 

 gradually changed in the interest of the hygrophilous element, in 

 Australia the converse held, the tendency in favour of xerophilous 

 forms continuing into the present day. 



What was the climate of South- Western Australia during early 

 tertiary times ? Did the primitive tertiary flora flourish there as in 

 other parts of the world ? There is no reason to doubt that it did, 



1 "Report of the Work of the Horn Scientific Expedition," p. 70. 



2 Reported in Nature, vol. lvii. p. 495 (1898). A supposed Queensland case is also 

 alluded to here. 



