southeast, but which has in the course of time become differentiated from the Negroids and adapted to its peculiar surroundings. Toward the northwest we find the florid-skinned, blond-haired Europeans, whose ancestors are Mediterraneans and Asiatics, but whose distinguishing characteristics were undoubtedly acquired during the course of their wanderings across the plain lands between the Pamir region and the Baltic. In the southeast section finally, dwell the swarthy-skinned, black-haired Indians, who came down from the northern plain lands during prehistoric days and established their supremacy over the scarcely differentiated black people of the peninsula. These distinctions are not to be taken too definitely, however; for even as the three sections of the Indo-Mediterranean-European section are interconnected, so the corresponding ethnic types are blended along the lines of transition, in such a way that it is as easy to pass from diversity to unity as from unity to diversity in considering the characteristics of the Caucasians.
Before leaving the eastern hemisphere to consider the fourth racial region on the other side of the globe, we should take a hasty survey of the insular region of Oceania and determine the ethnic affinities of the South Sea Islanders. These islands of the Pacific are so scattered, and differ from one another so widely, that they cannot be said to constitute a separate racial region. The most that can be done in the way of classification, therefore, is to divide the archipelagoes into groups, establish their relations with each other, and indicate their connections with the mainland.
Topographically the islands may be divided into two classes: continental and oceanic. The continental islands are adjacent to the mainland and stretch out along the equator toward the east and southeast. The oceanic islands, on the other hand, are grouped between the tropics in isolated archipelagoes, extending more than halfway across the Pacific. The lines of entry into this insular region lead back to Indo-Malaysia, the cradle-land of mankind and the point of intersection of the three racial regions of the old world. Oceania was, accordingly, peopled from three sources, successive waves of Negro, Caucasic and Mongolic migration coming together in Indo-Malaysia and spreading out again over the islands of the Pacific.
The negro dispersion occurred first, probably in the early days when the eastern-equatorial region still extended uninterruptedly far out into the South Sea. As the configuration of the globe assumed its historic form, many of the earlier land-bridges were broken, leaving the blacks to become adapted to different insular environments. But as the islands occupied were for the most part continental and situated under the equator, the surrounding conditions differed but slightly from those prevailing throughout the eastern-equatorial region. As a