Thus, on both continents, gigantic reptiles long time. swayed the sceptre over the entire animal creation. But their empire was approaching its end. One of those throes of Nature, through which new annexations of land to the continent were ef fected, ushered in the closing stage of Mesozoic Time. The conditions of life were changed; all the peculiar types whose history we have traced dropped out of existence, and mammals assumed the reins of empire. Turtles received accessions of numbers, and serpents now first uncoiled their sinuous lengths, while batrachians made the bayous and marsh es resonant with the varied piping of a myriad voices. ་ །། ། Fig. 76. The Hadrosaurus. Among the latter a salamander, known as Andrias Scheuchzeri, has attracted most attention, in consequence of having for a long time been regarded as the skeleton of a man, who thus, by the fossilization of his remains, was supposed to attest the reality of the Deluge of Noah. Such is a hasty glance at the Age of Reptiles. Success I ive phases of animal life have swept like waves over the surface of our planet, but none has been more striking or more real than that which was dominant through Mesozoic time. Throughout the whole extent of Great Britain there has not been known a single large reptile during the human era; yet in the single era of the Wealden the British dominions maintained four or five species of Dinosaurs fifteen to twenty feet in length, ten or twelve Crocodilians, Lacertians, and Enaliosaurs ten to fifty or sixty feet in length, besides Pterosaurs and Turtles, to say nothing of the probably numerous species whose fossil remains have as yet escaped observation. These successive swells in the stream of animal life are convenient stand-points from which to note the progressive development of organic existence. The history of reptiles, like that of fishes, presents some remarkable exceptional features, which have a most important bearing upon the question of "development," which is taking a front rank among the questions of the age. But these aspects of the case are reserved for future consideration. CHAPTER XVII. THE GEOGRAPHY OF THE EMPIRE OF REPTILES. ONTINENTS have been developed, like organisms, CONTI from their primeval germs. Geologic force, like vital force, operates always toward the accomplishment of some definite end; and, notwithstanding its vicissitudes, there is little difficulty in perceiving how every phenomenon of one age has been contemplated and ministered to by the events of all preceding ages. The American Continent is not a single upthrow of volcanic force, but a gradual growth, beginning before the creation of the first animals and plants, and proceeding by a certain method through all the subsequent ages even to the present, and receiving from time to time such progressively improved existences as its physical circumstances permitted. At first it was an angulated ridge of land in the centre of the present continental area (Fig. 20). Then, by successive upheavals, belts of increment were added on the southeast and southwest, till the ancient ocean has been narrowed to its present limits. Like the exogenous growth of an oak, the increase has been always upon the outside. So the vast continent has been built up and configurated in accordance with a method as definite as that which has shaped the globe itself. The empire of molluscs saw the greater portion of the continent the bed of the sea. The reign of fishes witnessed the emergence of only the extreme northeastern and northwestern portions of the United States (Fig. 55). In the earlier part of the reign of reptiles New England was a peninsula hemmed in by the broad estuary of the St. Law rence on the north, and a similar estuary of the embryo. Connecticut on the west (Fig. 67). Toward the close of this reign the continent had assumed the similitude of its present form and extent (Fig. 77). The Atlantic coast stretched from the neighborhood of New York City to the Delaware River, and thence southwestward to South Carolina, along a line now sixty or seventy miles inland. Delaware and Chesapeake Bays were consequently out at sea, and the Delaware River emptied into the Atlantic at Trenton. From South Carolina the shore-line turned gradually westward, and crossed the States of Georgia, Alabama, and Mississippi at the distance of one or two hundred miles from the present gulf coast. A deep bay set northward along the future valley of the Mississippi River as far as the mouth of the Ohio, or beyond, so that at this time the confluence of those two rivers was at their mouth. West of the Missouri was a vast inland sea or elongated gulf, which stretched along the eastern flanks of the Rocky Mountains to the Arctic Ocean. This gulf was perhaps interrupted at one or two places by spurs of the mountains. Into this gulf emptied the Athabasca, Slave, and Great Bear Lakes. The upper watershed of the present Missouri was beneath the sea; and the basin of the Mississippi was more limited in extent than that of the Ohio, which probably was the larger stream. West of this Mediterranean Gulf was a broad belt of land stretching from the isthmus far to the northwest, and probably to Behring's Straits, if not across them. The Pacific coast was a hundred and fifty miles farther inland than at present. Lake Superior was the only one of the great lakes then in existence. The stream which drained it wound past the future sites of Detroit, Cleveland, and Buffalo, and, plunging over the escarpment near Lewiston, became the ancestor of the present St. Lawrence. The basins of the other lakes are the result of later geological agencies. Probaly large portions of Greenland and other arctic lands had emerged, besides the principal portion of the West India Islands. The climate of the period was much warmer than that of the same localities in the present age. Coral-builders, and other marine animals now restricted to tropical regions, then flourished throughout the whole length of the continent, from latitude 60° north to the Straits of Magellan on the south. The superior warmth of former ages of the world is probably due, in some measure, to the more highly heated condition of the globe-a source which, through all ages, has been undergoing a gradual diminution. It has also been suggested that the connection which existed between the Gulf of Mexico and the Arctic Ocean permitted the Gulf Stream to flow through the centre of the continent, and thus, while it carried a tropical temperature far toward the north, ameliorated the climate of the regions to the east of it, as the same ocean stream now moderates the cold of high latitudes upon European shores. Thus, while the Northern States were terra firma, the rich cotton-fields. of Alabama and Texas were gathering their calcareous sediments beneath the Gulf of Mexico. Fleets might have sailed over the rolling prairies of Kansas and Dacotah, and the anchor of the mariner might have fastened in the summit of Pike's Peak. But fleets of Nautili, and their cousins the Ammonites, were the only keels that plowed that Mediterranean sea, and the polyp and the oyster were the only mariners that cast their anchor on the sunken ridges. Eastward, the broad rolling plains of Illinois and Ohio were. adorned with a growth of sub-tropical vegetation, and the west wind of even a winter sky breathed softly over its never-fading foliage. But the shining cities of the West were not there. The kingly alligator alone disturbed the waters of the Ohio. The railroad car, the church spire, the |