CHAP. XIII.] 
THE AUSTRALIAN REGION. 
465 
few observations will therefore suffice, on the supposed early 
history of the Australian region as a whole. 
It was probably far back in the Secondary period, that some 
portion of the Australian region was in actual connection with 
the northern continent, and became stocked with ancestral forms 
of Marsupials ; but from that time till now there seems to have 
been no further land connection, and the Australian lands have 
thenceforward gone on developing the Marsupial and Monotre- 
mate types, into the various living and extinct races we now find 
there. During some portion of the Tertiary epoch Australia pro- 
bably comprised much of its existing area, together with Papua 
and the Solomon Islands, and perhaps extended as far east as the 
Fiji Islands ; while it might also have had a considerable exten- 
sion to the south and west. Some light has recently been thrown 
on this subject by Professor McCoy’s researches on the Pale- 
ontology of Victoria. He finds abundant marine fossils of 
Eocene and Miocene age, many of which are strikingly similar 
to those of Europe at the same period. Among these are Ceta- 
ceans of the genus Squalodon ; European species of Plagiostom- 
ous fishes; mollusca and corals closely resembling those of 
Europe and North America of the same age, — such as numerous 
Volutes closely allied to those of the Eocene beds of the Isle of 
AY yht, and the genus Dentalium in great abundance, almost or 
quite identical with European tertiary species. Along with 
these, are found some living species, but always such as now 
live farther north in tropical seas. The Cretaceous and Meso- 
zoic marine fossils are equally close to those of Europe. 
The whole of these remains demonstrate that, as in the 
northern so in the southern hemisphere, a much warmer climate 
prevailed in the Eocene and Miocene periods than at the present 
time. This is a most important result, and one which strongly 
supports Mr. Belt’s view, before referred to, that the warmer 
climates in past geological epochs, and especially that of the 
Miocene as compared with our own, was caused by a diminution of 
the obliquity of the ecliptic, leading to a much greater uniformity 
of the seasons for a considerable distance from the equator, and 
greatly reducing the polar area within which the sun would ever 
H R. 
