BY SYDNEY B. J. SKERTCHLY. 63 
Java or Palawan, or one of the many of the lovely isles of 
the Indian Archipelago, stretched some 2000 miles from 
Cape York to Tasmania. Probably it was connected with 
New Guinea also. This was Australia Orientalis. On the 
other side of the Opal Sea to the west, a large compact 
island, ike Borneo without its high mountains, which in all 
probability extended much further west than the present 
coast. This was Australia Vera. Between these were 
smaller islands, some quite mountainous. What climate 
must they have inevitably enjoyed ? 
30. Surely not an extreme one such as prevails now. 
In the first place there was a free mingling of warm waters 
from the north and cooler waters from the south, whose 
joint action was to ameliorate the heat. The waters of 
the Opal Sea flung their vapours upwards into cloud- 
wreaths, which shed their life-giving burdens upon the 
many islands—there could have been neither drought nor 
fervent heat, any more than is experienced in the sister 
islands of the Far East. The mountains were higher 
then than now, and there is distinct evidence that in Tertiary 
times snow and ice were not unfrequent even in the neigh- 
bourhood of Brisbane. 
31. Nor is this a mere inference from  orographica 
conditions. There is positive evidence in the plants and 
animals. The first piece of evidence is negative, and I 
may say it is almost too strongly in my favour—too perfect. 
I have great hesitation in inferring temperature from life- 
forms so far back in time as to the Cretaceous : but as the 
paleontological is backed by the physical evidence, I dare 
not. omit it. In these waters of the Opal Sea of Cretaceous 
times no reef-building corals lived—they could not. It 
was not that the waters were too charged with sediment, 
for corals throve in the preceding eras, and in the fol- 
lowing Tertiary period. What a contrast to the Queens- 
land coast of to-day, with its 1,200 mile long Barrier Reef ! 
It certainly looks as if the wat>rs of the Opal Sea were too 
cool to allow of such growth, and when we remember tbat 
there was free ingress fom the Antarctic we may see therein 
at any sate a partial explanation. Still, I would not trust 
to this alone. 
32. Far stronger is the story told by the Tertiary 
