Nor would the land animals be less actively employed in maintaining the laws of their creation. No skeletons of birds have yet been detected; but their foot-prints, we have seen, are numerous. These clouds of insects, and other brilliant objects that flit with such rapidity across the sky, have all been stirred, and are leaping they know not whither, for the tread of a monster’s feet is heard through the forest, mailed in plated horn thicker than Ajax’s shield, and, pursued by another, presses and plunges onward in reckless haste. Imagine the many encounters during a single season between one set of the terrestrials only, the saurians; of the class, there are the remains of the megalosaurus, the great saurian—of the geosaurus, the land saurian—of the hylæosaurus, the forest saurian—of the teleosaurus, the perfect saurian,—all fitted with jaws and teeth, most cruelly bent on mischief, and restrained by no brotherly sympathies when accident or bold defiance bring them in the way of each other. The fell onslaughts of generous man, tribe against tribe, clan to clan, nation to nation, for some inconceivable nothing or unintended provocation, recorded within the brief historical epoch, may reconcile one to a picture of the irrationals similarly engaged, and throughout periods of time sufficient for the deposition of the entire oolitic series, before which the rule of earthly dynasties shrinks into utter insignificance. These depositions accomplished, and successive races entombed within them, there is evidence that the floor of the ocean was raised above the waters, and that central Europe presented, all around, a breast of high land. There are various intercalations, in the series of marine and terrestrial deposits as well as of fresh and salt water fossils. Violent internal convulsions prevailed throughout the period, and the animals were all of a kind to care little for the war of the elements. Meanwhile a fresh water formation is completed in many places a thousand feet in thickness, and consisting of a series of beds; not continuous all round the shores of the oolitic detritus, but confined to a few localities, and characterized everywhere by its own group of organisms. This is the wealden formation. And the question arises, How this series of fresh water clays, and sands, and grits, was produced at a time when the sea prevailed so universally over the whole of continental Europe, and the eastern division of Great Britain? The solution is simpler than at first sight might appear, when viewed in connection with the existing distribution of all our great primary formations. The extent of dry land was such as to furnish watershed for numerous rivers. The mountains supplied the detrital matter. This was brought to the river’s mouth, where it formed deltas; or spread out on the floor of estuaries, where it received the few marine fossils which are found in the formation. Cast your eye along the geological map of western Europe, and—in the mountains