BY SYDNEY B. J. SKERTCHLY. 77 
that through the long Tertiary period the climate of Australia 
was deteriorating. The old universal flora had all the 
makings of the new flora in it—both the Orientalis and the 
Vera types—but when at last the Opal Sea became dry, 
only certain plants had adaptibility enough to battle with 
the increasing heat and decreasing moisture. The rest died. 
76. But there was a great difference between Australia- 
Orientalis and Australia-Vera. The former, owing to its 
mountainous and coastal character suffered less in climate 
—it has continued to receive fairly, and in parts quite, 
abundant rain and so a portion of the old flora has been 
preserved, in spite of its inferior adaptibility. This is the 
so-called Tropical Flora which I prefer to call Oriental. 
It is as has been said, essentially Asaitic in facies, but the 
bulk is not specifically identical with the Asiatic flora— 
it is merely the tropical part of the Universal flora. This 
portion of our present flora, then, I look upon as a true 
survival. 
77. Again Australia-Orientalis is still closely connec- 
ted with New Guinea, and undoubtedly, was recently in 
direct physical continuity therewith. Hence there has 
been a real Asiatic immigration, And it is going on still. 
78. I may remark, en passant, that it is considered as 
established that species become more vigorous, more able 
to cope with diverse conditions as they grow older—of 
course up to a certain age. Now if my contention be true, 
that our Flora as a whole is of modern date, the species 
should have comparatively small power of waging success- 
ful war against the sturdier denizens of botanically older 
lands. I do not lay much stress upon this, but we have 
learned to our cost, e.g., in the Prickly Pear and Water 
Hyacinth (Hichornia speciosa), how alarmingly rapid is 
the spread of certain foreign species, and it is stated that no 
Australian introduced species has anywhere run riotously 
wild. If there is any truth in this, it tells in my favour. 
But I have seen Mimosa pudica and Lantana, both S. 
American forms, as is the Water Hyacnith, do just as much 
damage in places like Borneo and the Malay States, where 
the flora is assuredly as old as any. Also I do not know that 
any Australian plants likely to riot have been introduced 
into the northern warm-temperate zone, and garden flowers 
