IX. _Characters of the cranium and of the face._ From the point of view of descriptive anthropology as well as from an anatomical point of view, the head is composed essentially of two regions, the cranium and the face. The former is covered solely by the hairy skin which follows all its contours, and it in reality therefore only presents osteological characters. The general form, proportions, etc., are almost the same in the living man as in the skeleton. I will therefore go into greater detail upon this subject when treating of the latter. Here 1 will only remark that the inequality of the skin and of some subjacent muscular fibres necessitates some corrections in the comparison of measurements taken from the living head and from the skull. For example, the presence of the temporal muscles increases to a sufficiently sensible extent the transverse maximum diameter. Consequently the ratio of the latter to the anterio-posterior diameter becomes raised. This ratio, which constitutes the _cephalic index_, is one of the characters which anthropologists employ most frequently, and it was important to determine the correction to be made in case of comparison. Broca has shown that it is two units when the ratio is expressed in the manner which I shall mention further on. The case is different with the face. Here the super-imposed soft parts play a part of which the importance has been alternately exaggerated or neglected. William Edwards considered that races should be determined, as we judge of individuals, solely by the facial characters. Serres, starting from the fact that the bony framework determines the general form and the proportion of the face, required that osteological characters only should be taken into account. Both were too exclusive. Doubtless the skeleton is important in the most superficial characters of the face. But the muscles, the cellular and adipose tissue, and the cartilages are much more developed on the face than upon the cranium; and from their greater or less extension, from their various relations, differences of feature result which constitute so many characters. Unfortunately it is often very difficult to define the latter. The most detailed descriptions are rarely sufficient, and the most exact measurements are far from giving an idea of certain variations of the human figure. For example, they cannot make the difference intelligible, which is nevertheless very sensible to the eye, which distinguishes the nose of a negro of Guinea from that of a Nubian negro.