shell. In some of the
larger specimens the ribs have not yet entirely coalesced.

The Crocodilians also appear in the later Triassic, abound in the
Jurassic, and give way before the later types, the true Crocodiles, in
the Cretaceous. They were marine animals with naked skin, a head and
neck something like that of the Ichthyosaur, and paddles like those of
the Plesiosaur. Their back limbs, however, were not much changed after
their adaptation to life in the sea, and it is concluded that they
visited the land to lay their eggs. The Teleosaur was a formidable
narrow-spouted reptile, somewhat resembling the crocodiles of the Ganges
in the external form of the jaws. The modern crocodiles, which replaced
this ancient race of sea-crocodiles, have a great advantage over them
in the fact that their nostrils open into the mouth in its lower depths.
They can therefore close their teeth on their prey under water and
breathe through the nose.

Snakes are not found until the close of the Mesozoic, and do not figure
in its characteristic reptile population. We will consider them later.
But there was a large group of reptiles in the later Mesozoic seas which
more or less correspond to the legendary idea of a sea-serpent. These
Dolichosaurs ("long reptiles") appear at the beginning of the Chalk
period, and develop into a group, the Mososaurians, which must have
added considerably to the terrors of the shore-waters. Their slender
scale-covered bodies were commonly twenty to thirty feet in length. The
supreme representative of the order, the Mososaur, of which about forty
species are known, was sometimes seventy-five feet long. It had two
pairs of paddles--so that the name of sea-serpent is very imperfectly
applicable--and four rows of formidable teeth on the roof of its mouth.
Like the Deinosaurs and Pterosaurs, the order was doomed to be entirely
extinguished after a brief supremacy in its environment.

From this short and summary catalogue the reader will be able to form
some conception of the living inhabitants of the Mesozoic world. It is
assuredly the Age of Reptiles. Worms, snails, and spiders were, we may
assume, abundant enough, and a great variety of insects flitted from
tree to tree or sheltered in the fern brakes. But the characteristic
life, in water and on land, was the vast and diversified family of
the reptiles. In the western and the eastern continent, and along the
narrowing bridge that still united them, in the north