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 the land there stalked huge reptiles fifty and sixty
feet long, and, when standing erect, at least thirty feet
high.<15> Some of these huge creatures were carnivorous, living
on other animals. Others fed on the foliage of trees. In the
air, huge reptilian bats, veritable flying dragons with a spread
of wings from ten to twenty feet, disported themselves.<16>
In the sea there swam great reptilian whales, seals, and