victorious exultation of tropical life in its full free development.

All through the Primary and Secondary epochs of geology, it is now
pretty certain, hothouse conditions practically prevailed almost
without a break over the whole world from pole to pole. It may be true,
indeed, as Dr. Croli believes (and his reasoning on the point I confess
is fairly convincing), that from time to time glacial periods in one or
other hemisphere broke in for a while upon the genial warmth that
characterised the greater part of those vast and immeasurable primæval
æons. But even if that were so--if at long intervals the world for some
hours in its cosmical year was chilled and frozen in an insignificant
cap at either extremity--these casual episodes in a long story do not
interfere with the general truth of the principle that life as a whole
during the greater portion of its antique existence has been carried on
under essentially tropical conditions. No matter what geological
formation we examine, we find everywhere the same tale unfolded in
plain inscriptions before our eyes. Take, for example, the giant
club-mosses and luxuriant tree-ferns nature-printed on shales of the
coal age in Britain: and we see in the wild undergrowth of those
palæozoic forests ample evidence of a warm and almost West Indian
climate among the low basking islets of our northern carboniferous
seas. Or take once more the oolitic epoch in England, lithographed on
its own mud, with its puzzle-monkeys and its sago-palms, its crocodiles
and its deinosaurs, its winged pterodactyls and its whale-like lizards.
All these huge creatures and these broad-leaved trees plainly indicate
the existence of a temperature over the whole of Northern Europe almost
as warm as that of the Malay Archipelago in our own day. The weather
report for all the earlier ages stands almost uninterruptedly at Set
Fair.