The jet or coal black color is not very widespread. It occurs in a narrow and more or less broken belt across Africa just south of the Sahara Desert, with a few scattering bits farther south on the same continent. Another center of dissemination of this characteristic, although widely separated from it, occurs in the islands southeast of New Guinea in the Pacific Ocean, in the district which is known from this dark color of its populations as Melanesia. Next succeeding this type in depth of color is the main body of negroes, of Australians, and of the aborigines of India. This second or brownish group in the above-named order shades off from deep chocolate through coffee-color down to olive and light or reddish brown. The American Indians fall within this class, because, while reddish in tinge, the skin has a strong brown undertone. In the Americas we find the color quite variable, ranging all the way from the dark Peruvians and the Mexicans to the aborigines north of the United States. The Polynesians are allied to this second group, characterized by a red-brown skin. A third class, in which the skin is of a yellow shade, covers most of Asia, the northern third of Africa, and Brazil, including a number of widely scattered peoples such as the Lapps, the Eskimos, the Hottentots and Bushmen of South Africa, together with most of the people of Malaysia. Among these the skin varies from a dull leather color, through a golden or buff to a muddy white. In all cases the shading is in no wise continuous or regular. Africa contains all three types of color from the black Dinkas to the yellow Hottentots. In Asia and the Americas all tints obtain except the jet black. There are all grades of transitional shading. Variations within the same tribe are not inconsiderable, so that no really sharp line of demarcation anywhere occurs.
The fourth color group which we have to study in this paper is alone highly concentrated in the geographical sense. It forms the so-called white race, although many of its members are almost brown and often yellow in skin color. As we shall show, its real determinant characteristic is, paradoxically, not primarily the skin but the pigmentation of the hair and eyes. Nevertheless, so far as it may be used in classification, the very light shades of skin are restricted to Europe, including perhaps part of modern Africa north of the Sahara, which geologically belongs to the northern continent. There is a narrow belt of rather light-skinned peoples running off to the southeast into Asia, including the Persians and some high-caste Hindus. This offshoot vanishes in the Ganges Valley in the prevailing dark skin of the aboriginal inhabitants of India. The only entirely isolated bit of very light skin elsewhere occurs among the Ainos in northern Japan; but these people are so few in number and so abnormal in other respects that
