Since a comparison of the fauna of South America and Africa, and a survey of the sea-bottom between those continents, have dispelled the dream of the ancient Atlantis, and relegated that land connection at least to the eocene period of the tertiary, no one can suppose the American man to have migrated from Africa or southwestern Europe. For other and equally solid reasons, no immigration of Polynesians can be assumed. Yet zoölogists, perfectly willing to derive man from an anthropoid, and polygenists to the utmost, hesitate to consider man an autochthon in the New World. There is too wide a gap between the highest monkeys and the human species in this continent.[29] Discoveries of fossil apes might bridge this, but none such has been reported. If we accept the theory that man as a species spread from one primal centre, and in the higher plasticity of his early life separated into well defined races, which became unalterably fixed not much later than the close of the glacial epoch—and this theory appears to be that now most agreeable to anthropologists—then the earliest Americans made their advent on this continent as immigrants. This is our first fact in their pre-historic chronology; but before we can assign it an accurate position on the scale of geologic time, we must await more complete discoveries than we now have at our command. We must also wait until our friends the geologists have come to some better understanding among themselves as to what took place in the pleistocene age. You have heard me talking freely about the glacial epoch and its extension in America; but geologists are by no means of one mind as to this extension, and a respectable minority of them, led by Sir J. William Dawson, deny the existence or even possibility of any continental glacier. What others point out as a terminal moraine they explain to be “nothing but the southern limit of the ice-drift of a period of submergence.”[30] It is clear that when we speak about the migration of the Americans at a time when the polar half of each continent was either covered with a glacier thousands of feet thick, or submerged to that depth beneath an arctic sea, we have to do with geographical conditions totally unlike those of to-day. I call attention to this obvious fact because it has not been obvious to all writers.