dexes between 75 and 80 are characterized as mesocephalic. The two skulls in our illustrations, viewed from above, show how marked the differences in these proportions may be. In very rare instances the index may run in individuals as low as 62, and it has been observed as high as 103—that is to say, the head being broader than it is long. In our study, which is not of individuals, but of racial groups, the limits of variation are of course much
less. We shall seldom find heads in any considerable numbers exceeding the limits roughly indicated by the two crania in our illustrations.[1]
A factor which is of great assistance in the rapid identification of racial types is the correlation between the proportions of the head and the form of the face. In the majority of cases, particularly in Europe, a relatively broad head is accompanied by a rounded face, in which the breadth back of the cheek bones is
- ↑ Our data are drawn in the main not from the relative proportions of each type of head occurring within a given area, but from general averages made up by including all head forms alike. The more scientific method would be to give the relative proportions of each type of head; but that is impossible with the present data. It is a comforting circumstance, however, that the results drawn from the average approximate closely enough to those obtained in the other way for all general purposes. Oftentimes, for lack of data, it is impossible to employ the more scientific method for detailed analysis. Anthropologists distinguish between the relative proportions of the head measured over all the soft tissues, giving the cephalic index, and those taken from the skull divested of all its fleshy parts, in which latter case the relation of length to breadth is expressed by the so-called cranial index. Experience has shown that the cephalic generally exceeds the cranial index by two units, more or less. In other words, the living head is relatively broader than the cranium by about three per cent. This would fix our extreme indices on the living head at about 72 and 89 for averages.
