golden wheat, the thronging population-these all were scenes and objects still shut up in the silence and night of the far-distant future. An intelligent being may have stood on the bank of the river, and pictured to himself the shifting scenes of the next half million of years, as we now portray to imagination the expansion of American civilization, and its destined continental grasp of empire a hundred years hence; but no intelligent hand impressed its influence upon the features fashioned by Nature. An occasional voice of monstrous Deinosaur broke the dreadful silence of the broad continent. No song of bird was heard in the grove, and rarely the hum of insect in the air. Bland as the breezes were, and seductive the climate, it was not a fit place for man to be in. Frogs and salamanders must be his pets-lizards and crocodiles his domestic animals. Providence reserved him for a more finished condition of the world.

CHAPTER XVIII.

THE REIGN OF MAMMALS.

NOTHER cycle of eternity was past. The progress of geological agencies had brought the crust of the earth to a tension which was to be relieved by another collapse. As the Paleozoic Time was closed by the sudden sinking of the beds of the Atlantic and Pacific Oceans, and the corresponding protrusion of the ridges of the Appalachians, so the Mesozoic Time was closed by a farther progress in the same direction. The ever-shrinking nucleus necessitated the ever-enlarging wrinkles of the enveloping crust. The furrows must deepen and the folds. must rise. The uplift which marked the close of Mesozoic Time affected the whole continental body. It was not a sudden uprising accomplished in a day. It may have extended through a century; but it was an interval of movements so much accelerated as to mark a pretty definite boundary between two stages of continental development. and two great periods in the history of the world. During the Cretaceous Age which had now just closed, the great Mediterranean Gulf represented in Fig. 77 had been broader along its eastern borders, and continuous to the Gulf of Mexico. Through this, perhaps, the Gulf Stream had coursed to the Frozen Ocean. Now, by an upheaval of the central region, this gulf was severed in twain. On the south it retreated to nearly the modern limits of the Mexican Gulf, while northward remained an elongated body of water, swelling out in the central portion of the continent, in two places, to dimensions exceeding the Caspian and

Black Seas of the Old World. Indeed, the area covered by this shallow expanse of deserted and isolated sea-water was the Lectonia of the New World, which, like the level region in the south of Russia, once overflowed by the higher waters of the great seas which stretch along the confines

Fig. 77. Outlines of the North American Continent at the end of Mesozoic Time. The existing boundaries are indicated by dotted lines.

a, a, a. The great Tertiary Sea, stretching from the Arctic Ocean, along the eastern flanks of the Rocky Mountains, to Texas. b, b. The great "Central Plateau,” in modern times a worn-out continental area.

of the two continents, was destined to be gradually drained. The drainage in both cases was effected partly by the upraising of the continent, and partly by the bursting of barriers and deepening of channels at the point where the imprisoned waters were escaping. But, while the drainage

of the European Lectonia was an event which reaches down within the grasp of human tradition, the drainage of the American Lectonia was an event shrouded in the obscurities of the pre-Adamic ages. Thus again we discover that the "New World" is in reality the oldest.

This broad expanse of Tertiary waters stretched across the western part of Dakotah and Nebraska. At the same time, the Mexican Gulf, though outlined somewhat after the modern fashion, was left a hundred miles more extended than at present on the west and north, and reached its long arm up the valley of the Mississippi to the mouth of the Ohio, beckoning to the cooler waters of the North to come and lave its tropic shores. This arm was the southern representative of the Gulf of the St. Lawrence. The peninsula of Florida was a coral reef. A broad belt of the Atlantic States to New York was yet a sea-bottom, and the Pacific yet held possession of the lowland zone of the western slope. Now the Missouri River came into existence, born of the great central sea. Still the Niagara River thundered away in an ancient excavation, which, like the work of the men of Nineveh, was destined to be buried beneath the rubbish of coming ages, and lie a long time unremembered. Now the eastern ranges of the Rocky Mountains were first lifted above the deep. During subsequent ages they underwent further upheavals, while the waters of the Gulf and the great oceans were rolled back to their present positions.

The epoch which followed the last great upheaval, and witnessed the events transpiring on the shores of the American Mediterranean, marked the dawn of the present order of things. All subsequent time has hence been styled Cenozoic. The populations which swarmed upon the earth during each preceding epoch disappeared in turn, and their places were occupied by forms generally more

advanced. Of the thousands of species that had their being during the Paleozoic and Mesozoic Ages, not one has survived to the present. The specific types are all extinct. Now, on the contrary, in the dawn of the Cenozoic Ages, a fauna was created, of which a few representatives have survived to modern times. The survivors, however, are all marine. Another feature of the fauna of this era, indicating the approach of the human period, was the advent of multitudes of mammals, a class of which man is the head. Some of the lowest terrestrial mammals seem, it is true, to have made their appearance a long time previously in the Jurassic Age, and perhaps even in the Triassic, but nothing more is seen of the class till the beginning of the Tertiary. Like the Devonian reptiles, they seem to have run far in advance of their class, and to have totally perished for their temerity. The full numerical development and ascendency of mammalian quadrupeds are the characteristics of the Tertiary Age.

The immortal George Cuvier was the first to bring to light abundant relics of these masters of a former world. The vicinity of Paris seems to have been an ancient burying-place of extinct quadrupeds while it was yet the bed of the sea. The bones were undoubtedly transported thither from the adjacent land. One of the most remarkable of these animals was the Paleotherium, a three-hoofed quadruped resembling a tapir, and attaining the size of a horse. Other quadrupeds, which grazed upon the same grounds with the Paleothere, were variously allied to the deer, the peccary, and the tapir. Monkeys, mastodons, and elephants existed in Europe a little later, and these were associated with a huge anomalous quadruped named Dinotherium, which united characteristics of the elephant, hippopotamus, tapir, and dugong. The sloth and opossum tribes also, which are now confined to other continents,