As the American continent, in other respects so incomplete, is mostly separated from all the others; and its form is more simple and less complex than that of the ancient divisions of the globe, it well deserves our consideration in that point of view; and it may perhaps furnish the general type and true geographical outline of a continent in its natural state. A narrow isthmus connects the upper half, stretching in a widely extended tract towards the North Pole, and the inferior part, with its Southern peak; and thus both form, according to general impression but one and the same continent; and so prove, in fact, how totally the Northern and Southern parts of a continent may differ. That now in the period when the Euxine was still united to the Caspian, when the White sea stretched farther into land, and the Ural mountains formed an island, or were surrounded to the North and South by the sea, Asia and Europe were probably separated towards the North, is a point to which we have already had occasion to allude. But if, on the one hand, Europe were separated from Asia, it might on the other have been easily joined to Africa by an isthmus, where it is now divided from it by a straight, and so have formed with it one connected continent; in the same way as Australia is united with Asia, if at least we consider the long chain of islands between them as one unbroken continuity. Then in truth there would have been but three continents of a form similar to the above-mentioned one of America; except that the two nobler continents closely entangled with one another would not on that account have so well preserved the original conformation. That it is on the whole more correct, and more consonant with nature, as well as with theory, to suppose the existence of only three original portions of the globe, might be shown by much additional evidence.