Evergreens which now need the warmth
of Italy or the Riviera then flourished in Lapland and Spitzbergen.
The flora of Greenland--a flora that includes magnolias, figs, and
bamboos--shows us that its temperature in the Eocene period must have
been about 30 degrees higher than it is to-day. [*] The temperature of the
cool Tyrol of modern Europe is calculated to have then been between 74
and 81 degrees F. Palms, cactuses, aloes, gum-trees, cinnamon trees,
etc., flourished in the latitude of Northern France. The forests that
covered parts of Switzerland which are now buried in snow during a great
part of the year were like the forests one finds in parts of India and
Australia to-day. The climate of North America, and of the land which
still connected it with Europe, was correspondingly genial.

* The great authority on Arctic geology, Heer, who makes
this calculation, puts this flora in the Miocene. It is now
usually considered that these warmer plants belong to the
earlier part of the Tertiary era.

This indulgent period (the Oligocene, or later part of the Eocene),
scattering a rich and nutritious vegetation with great profusion over
the land, led to a notable expansion of animal life. Insects, birds, and
mammals spread into vast and varied groups in every land. Had any of the
great Mesozoic reptiles survived, the warmer age might have enabled them
to dispute the sovereignty of the advancing mammals. But nothing more
formidable than the turtle, the snake, and the crocodile (confined
to the waters) had crossed the threshold of the Tertiary Era, and the
mammals and birds had the full advantage of the new golden age. The
fruits of the new trees, the grasses which now covered the plains, and
the insects which multiplied with the flowers afforded a magnificent
diet. The herbivorous mammals became a populous world, branching into
numerous different types according to their different environments.
The horse, the elephant, the camel, the pig, the deer, the rhinoceros
gradually emerge out of the chaos of evolving forms. Behind them,
hastening the course of their evolution, improving their speed, arms,
and armour, is the inevitable carnivore. He, too, in the abundance of
food, grows into a vast population, and branches out toward familiar
types. We will devote a chapter presently to this remarkable phase of
the story of evolution.

But the golden age closes, as all golden ages had done before it, and
for t