agging themselves on their bellies as do the lizard and
alligator, their lower kindred. Others became flying creatures like
our bats, only vastly larger, often with a spread of wing of fifteen
or twenty feet. Yet others, even as strangely shaped, dwelt with the
sharks in the sea.

[Illustration: FIG. 9. REPTILES OF JURASSIC PERIOD.]

In this time of the earth's history we have the first bird-like forms.
They were feathered creatures, with bills carrying true teeth, and
with strong wings; but they were reptiles in many features, having
long, pointed tails such as none of our existing birds have. They show
us that the birds are the descendants of reptiles, coming off from
them as a branch does from the parent tree. The tortoises began in
this series of rocks. At first they are marine or swimming forms, the
box-turtles coming later. Here too begin many of the higher insects.
Creatures like moths and bees appear, and the forests are enlivened
with all the important kinds of insects, though the species were very
different from those now living.

In the age of reptiles the plants have made a considerable advance.
Palms are plenty; forms akin to our pines and firs abound, and the old
flowerless group of ferns begins to shrink in size, and no longer
spreads its feathery foliage over all the land as before. Still there
were none of our common broad-leaved trees; the world had not yet
known the oaks, birches, maples, or any of our hard-wood trees that
lose their leaves in autumn; nor were the flowering plants, those with
gay blossoms, yet on the earth. The woods and fields were doubtless
fresh and green, but they wanted the grace of blossoms, plants, and
singing-birds. None of the animals could have had the social qualities
or the finer instincts that are so common among animals of the present
day. There were probably no social animals like our ants and bees, no
merry singing creatures; probably no forms that went in herds. Life
was a dull round of uncared-for birth, cruel self-seeking, and of
death. The animals at best were clumsy, poorly-endowed creatures, with
hardly more intelligence than our alligators.

The little thread of higher life begun in the Microlestes and
Dromatherium, the little insect-eating mammals of the forest, is
visible all through this time. It held in its warm blood the powers of
the time to come, but it was an insignificant thing among the mighty
cold-blooded reptiles of these ancient lands. There are