togaeal province. But, at the end of the
Triassic period, the movement of depression recommenced in our area,
though it was doubtless balanced by elevation elsewhere; modification and
development, checked in the one province, went on in that "elsewhere";
and the chief forms of Mammals, Birds and Reptiles, as we know them, were
evolved and peopled the Mesozoic continent. I conceive Australia to have
become separated from the continent as early as the end of the Triassic
epoch, or not much later. The Mesozoic continent must, I conceive, have
lain to the east, about the shores of the North Pacific and Indian
Oceans; and I am inclined to believe that it continued along the eastern
side of the Pacific area to what is now the province of Austro-Columbia,
the characteristic fauna of which is probably a remnant of the population
of the latter part of this period.

Towards the latter part of the Mesozoic period the movement of upheaval
around the shores of the Atlantic once more recommenced, and was very
probably accompanied by a depression around those of the Pacific. The
Vertebrate fauna elaborated in the Mesozoic continent moved westward and
took possession of the new lands, which gradually increased in extent up
to, and in some directions after, the Miocene epoch.

It is in favour of this hypothesis, I think, that it is consistent with
the persistence of a general uniformity in the positions of the great
masses of land and water. From the Devonian period, or earlier, to the
present day, the four great oceans, Atlantic, Pacific, Arctic, and
Antarctic, may have occupied their present positions, and only their
coasts and channels of communication have undergone an incessant
alteration. And, finally, the hypothesis I have put before you requires
no supposition that the rate of change in organic life has been either
greater or less in ancient times than it is now; nor any assumption,
either physical or biological, which has not its justification in
analogous phenomena of existing nature.

I have now only to discharge the last duty of my office, which is to
thank you, not only for the patient attention with which you have
listened to me so long to-day, but also for the uniform kindness with
which, for the past two years, you have rendered my endeavours to perform
the important, and often laborious, functions of your President a
pleasure instead of a burden.

End of the Project Gutenberg EBook of Discourses, by Thomas H.