Page:The Outline of History Vol 1.djvu/166

 divisions, and they disregard the perpetual mixing where the main groups overlap.

§ 3

Whether the "Caucasian" race is to be divided into two or three main subdivisions depends upon the classificatory value to be attached to certain differences in the skeleton and particularly to the shape of the skull. The student in his further reading will meet with constant references to round-skulled (Brachycephalic) and long-skulled peoples (Dolichocephalic). No skull looked at from above is completely round, but some skulls (the dolichocephalic) are much more oblong than others; when the width of a skull is four-fifths or more of its length from back to front, that skull is called brachycephalic; when the width is less than four-fifths of the length, the skull is dolichocephalic. While some ethnologists regard the difference between brachycephaly and dolichocephaly as a difference of quite primary importance, another school—which the writer must confess has entirely captured his convictions—dismisses this as a mere secondary distinction. It seems probable that the skull shapes of a people may under special circumstances vary in