276 SPENCER MOORE [ocToBER 
It will be well here to refresh the reader’s memory by giving a 
short réswmé of the ideas enumerated with such acumen by Mr, 
Wallace. The fact that this celebrated naturalist’s conclusions respect- 
ing the geological history of Australia are faulty, should in no wise 
render us blind to the immense ability revealed in his brilliant pages, 
one’s only regret concerning which is that the requisite data were not 
to hand when the work was undertaken. Mr. Wallace holds that at 
one period, perhaps during the middle or latter part of the secondary 
epoch, Australia was connected with land lying to the north, whence 
it received the ancestors of its Monotremes and Marsupials. As he 
points out, for such a connection the general level of the country 
would have to be raised at least by 6000 feet, and this would change 
the whole country, including the deserts of the interior as well, into a 
mountainous and well-watered region, and in such a region the rich 
and peculiar flora characteristic of the south-west (the Autochthonian 
flora of Professor Tate) was evolved. While the western flora was in 
process of evolution, Eastern Australia, if it had arisen from the ocean, 
must have been widely separated from Western Australia, so that the 
present continent then consisted of a large and fertile Western Island, 
and a long and narrow island stretching from far south of Tasmania to 
New Guinea, with one or more large islands to the north. A depres- 
sion afterwards occurred which buried the greater part of North 
Australia beneath the ocean; whence it emerged in the middle or 
latter part of the tertiary period, and was stocked with vegetation from 
South-West Australia on the one hand, and from Indo-Malaya on the 
other. The flora of Eastern Australia has been derived from three 
sources: its south temperate element coming from Antarctic lands, 
the tropical element of Polynesian types from the north or north- 
east, and the typical Australian from across the dividing strait. 
Thus Mr. Wallace accounts for the “mixed” flora of Eastern, the 
isolated flora of Western, and the intermediate flora of Northern 
Australia. 
There are several objections to these views of Mr. Wallace. One, 
the existence in tertiary times of a sea separating the eastern and 
western part of the continent, has, as we have seen, no warrant from 
ascertained facts of geology, neither is there evidence for the sub- 
mergence of Northern Australia on a wide scale at the period when 
Mr. Wallace supposes it to have taken place. Moreover, unless the 
Mesozoic upheaval was accompanied by much differential movement, 
the upraised area would be converted, not into a mountainous region, 
but into a raised plateau; while if mountain ranges of the sup- 
posed height were formed at all, their disappearance, with the excep- 
tion of some insignificant hills, from hundreds of miles of country is 
wholly inconceivable. Besides, unless the geological record be extra- 
ordinarily defective, the date of the introduction of Marsupials is too 
early, seeing that remains of those animals are, with one exception in 
