during the extended Paleozoic time.

We can easily see, from the foregoing, how appropriately this period has
been named that of old life forms. In imagination we can recall a scene
of this old age. The air is sultry and full of vapors. The soil seems
hot and steaming. This is a veritable forest, but we see none of the
beautiful flowers which we associate with tropical vegetation to-day. In
the branches of the graceful tree-ferns, we will look in vain for birds.
They were yet far in the future. Neither were there any of the higher
orders of animals present. Not a single representative of the great
class of mammals enlivened the depths of the forest. There were fishes
in the waters, but not the fishes of to-day. Some true reptiles and
amphibians disported themselves in swampy jungles, but they were
unimportant. Almost the only sound to break the stillness, was the hum
of marsh-loving insects, the whistling of the wind, and the roar of
the tempests, which we may well believe raged with the more than tropic
severity of the present.<12>

The time at last came for the dawning of a new era. Vast changes had
been taking place in the geography of both continents. The region to the
south-west of the Green Mountains was upturned. The Alleghany Mountains
were formed, and the region east of the Mississippi River became part of
the stable land of the continent.<13> In Europe, nearly as great changes
occurred. The conditions of life must have been greatly modified by
these geographical changes. The life-forms bear testimony to this
changed condition. Old forms die away, and are succeeded by those
approaching more nearly our own times. The name of this period is the
Mesozoic time, or the period of middle life forms.<14> It is instructive
to notice the steady advance in the type of life, both animal and
vegetable. The abundant flowerless vegetation of the coal formation of
the preceding epoch dwindles away. But the flowering trees increase in
number and importance until, in the closing period of Mesozoic time, we
have trees with deciduous leaves. A great many of our forest trees had
representatives in the forests of that epoch.

Illustration of Ichthyosauri.-----------

Palms and species like the big tree of California were growing side by
side with species akin to our own common trees. But in the animal
world there were many strange forms. This was the age of reptiles. They
domineered on the land, in the air, and in the sea. On