|1914|Obercassel, near |Two skeletons, male |Crô-Magnon. | | | Bonn, Germany. | and female. | | +---------------------------------------------------------------------+ In his classic lecture of 1844, _On the Form of the Head in Different Peoples_, Anders Retzius laid the foundation of the modern study of the skull.(8) Referring to his original publication, he says: "In the system of classification which I devised, I have distinguished just two forms, namely, the _short_ (round or four-cornered) which I named _brachycephalic_, and the _long_, oval, or _dolichocephalic_. In the former there is little or no difference between the length and breadth of the skull; in the latter there is a notable difference." The expression of this primary distinction between races is called the _cephalic index_, and it is determined as follows: Breadth of skull × 100 ÷ length of skull. In this sense the primitive men of the Old Stone Age were mostly 'dolichocephalic,' that is, the breadth of the skull was in general less than 75 per cent of the length, as in the existing Australians, Kaffirs, Zulus, Eskimos, and Fijians. But some of the Palæolithic races were 'mesaticephalic'; that is, the breadth was between 75 per cent and 80 per cent of the length, as in the existing Chinese and Polynesians. The third or 'brachycephalic' type is the exception among Palæolithic skulls, in which the breadth is over 80 per cent of the length, as in the Malays, Burmese, American Indians, and Andamanese. [Illustration: FIG. 1. Outline of a modern brachycephalic skull (fine dots), superposed upon a dolichocephalic skull (dashes), superposed upon a chimpanzee skull (line). _g._ _glabella_ or median prominence between the eyebrows. _i._ _inion_--external occipital protuberance. _g-i._ glabella-inion line. Vertical line from _g-i_ to top of skull indicates the height of the brain-case. Modified after Schwalbe.] The cephalic index, however, tells us little of the position of the skull as a _brain-case_ in the ascending or descending scale, and following the elaborate systems of skull measurements which were built up by Retzius(9) and Broca,(10) and based chiefly on the _outside_ characters of the skull, came the modern system of Schwalbe, which has been devised especially to measure the skull with reference to the all-important criterion of the size of the different portions of the brain, and of approximately estimating the cubic capacity of the brain from the more or less complete measurements of the skull. Among these measurements are the slope of the forehead, the height of the median portion of the skullcap, and the ratio between the upper portion of the cranial chamber and the lower portion. In brief, the seven principal measures which Schwalbe now employs are chiefly expressions of diameters which correspond with the number of cubic centimetres occupied by the brain as a whole.