82 THE ORIGIN OF AUSTRALIA 
have grown and diminished. She was once farstretched 
westwards into the Indian Ocean. The depths of her west 
coast are but of yesterday—the movement is still going on. 
And she is connected with the upheavals and depressions 
of the great islands of the Indian archipelago, with the 
building of the mighty Himalayas. 
97. The islands, great and small, included within the 
Australian Region of zoology, are genetically connected 
with the Australian continent. And so is far-off New 
Zealand. 
98. Moreover, Australasia has, in times past, been 
linked with Antarctica, with S. Africa, and with S. America 
—but all before the eras this paper treats of. These, and 
other matters of equal fascination, I am reluctantly com- 
pelled to pass by in silence—for the present. 
XII. CONCLUSIONS. 
99. The conclusions I have arrived at, and I hope 
established, may be thrown into a few condensed para- 
graphs. 
100. The views here set forth are an expansion of those 
propounded by Dr. A. R. Wallace in his “ Island Life.” 
101. They differ fundamentally therefrom in recog- 
nising that the present Flora and Fauna are the result of 
the obliteration of the Opal Sea, and the consequent altera- 
tion of the Australian climate. Also in deriving both the 
Tropical and Extra-tropical Floras from the Tertiary 
universal Flora, and in allowing only a small proportion 
as true Asiatic immigrants. But chiefly in making all our 
land mammals to be late Tertiary forms ; not derived from 
pre-existing Australian forms, but entirely new species 
evolved to meet the new climatic conditions. The course 
of events was as follows :-— 
102. In Cretaceous times Australia was an archipelago, 
consisting of Australia-Orientalis on the east, a long 
mountainous island: of Australia-Vera to the south-west, 
with extension westwards beyond the present coast: and 
an intermediate island-studded sea, the Opal Sea. 
103. At this time there were no land mammals, nor 
did any arrive till, in late Tertiary times, the Opal Sea 
was no more. 
