BY SYDNEY B. J. SKERTCHLY. 83 
104. The climate was at first equable, mild, and the 
land copiously watered. 
105. Steady elevation ensued, and went on through 
the Tertiary period, till the archipelago became the con- 
tinent of Australia. 
106. The climate rapidly deteriorated, and grew hot 
and dry, and the land became semi-desert, partly from 
diminished rainfall, partly from absorption by the Braystone-. 
107. Many of the original plants died out: the rest 
became profoundly modified. But as the old Australia- 
Orientalis suffered least climatic change, its plants retained 
more of their original character, and constitute the 
so-called Tropical or Asiatic flora. A small contingent 
of genuine Asiatic forms came across from Asia. 
108. In late Tertiary times Australia was invaded by 
land mammals, mostly placental, with a few doubtful 
polyprotodont forms. The mass of the placentals developea 
aplacental characters and became our Diprotodonts, and 
perhaps, some became polyprotodont. The Bats and 
Rodents had no need to change, being sufficiently adaptable 
to thrive under the present climate. 
109. Hence both our present Flora and Fauna are the 
direct result of the deterioration of climate consequent 
upon the obliteration of the Opal Sea. But whereas the 
Flora had a pre-existing basis to build upon, the land 
mammals were entirely new-comers. There being no 
competition, the rapid development of new types had every 
opportunity of taking place. The conditions were abso- 
lutely unique. 
110. Hence, AUSTRALIA IS, IN REALITY, THE 
ONLY *“‘ NEW WORLD.” 
Sypney B. J. SKERTCHLY. 
