When these rocks were in the progress of formation, there existed the ichthyosaurus, or fish-lizard, which appears, in many respects, to have resembled the crocodile of the Nile. It was a predatory creature of enormous power, and must have been the tyrant and terror of the seas which it inhabited. Its alligator-like jaws, its powerful eye, its fish-like fins, and turtle-like paddles, were all formed to facilitate its progress as a destructive minister. The plesiosaurus was, if possible, a still more extraordinary creation. To the head of a lizard was united an enormously long neck, a small and fish-like body, and the tail of a crocodile: it appears formed for existence in shallow waters, so that, when moving at the bottom, it could lift its head above the surface for air, or in search of its food. The flora of this period must have been extensive; and it resembled the vegetation which exists at present in Tropical regions. We pass now to a new epoch, which is well distinguished by its animals from all that had preceded it. Races of reptiles still have place upon the earth, and we have now the megalosaurian remains; these animals possessing a strength and rapacity which would render them objects of terror as well as astonishment, could they be restored to the world which they once ravaged. An enormous bat-like creature also existed at this time--the pterodactyl--which, in the language of Cuvier, was, “undoubtedly, the most extraordinary of all the beings of whose former existence a knowledge is granted to us, and that which, if seen alive, would appear most unlike anything that exists in the present world.” “You see before you,” says the same writer, “an animal which, in all points of bony structure, from the teeth to the extremities of the nails, presents the well-known saurian characteristics, and of which no one can doubt that its integuments and soft parts, its scaly armour and its organs of circulation and reproduction, are likewise analogous. But it was, at the same time, an animal provided with the means of flying; and, when stationary, its wings were probably folded back like those of a bird, although, perhaps, by the claws attached to its fingers, it might suspend itself from the branches of trees.”[235] From the disintegration of the older rocks have no doubt arisen those formations which are known as the oolitic series. In these strata are preserved the remains of plants and animals more resembling those which now exist upon the earth; and, for the first time,--unless the evidence of the footsteps of birds on the new red sandstone of America be accepted,--we meet with the remains of the feathered tribes. In these formations we discover animals belonging to the class Mammalia,--the amphitherium and the phascolotherium,--which appear to have resembled, in many respects, the marsupial animals of New Holland.[236]