Among numerous other measurements which give indications for certain characters we must cite: the minimum frontal diameter (Fig. [12], S J); the interorbital line; the length and the breadth of the palate, the relation of which constitutes the palatal index, etc. Among the measurements of the curves it is necessary to note the horizontal circumference of the head, the antero-posterior curve with its frontal, parietal, and occipital portions, etc. Besides the facial angles, a great number of others are taken; the more important are the sphenoidal angle and the different occipital angles (of Daubenton, Broca, etc.), which give the inclination of the occipital foramen in relation to a horizontal plane. The measurements of these angles furnish valuable indications on the characters called seriary, to which we have recourse in order to compare man with animals which bear the closest resemblance to him.
FIG. 15.—Same subject as Fig. [14], seen in profile.
Example of nose concave and flattened, of prognathism, and of prominent superciliary arches.
(Photo. Prince Roland Bonaparte.)
But all these measurements do not suffice to exhaust the data of the morphology of the skull. There still remain a host of descriptive characters: the general form of the skull, pentagonal, oval, elliptical, etc.; the contour of the face more or less angular or rounded, its canine fossa more or less deep, its zygomatic arches, and its molar bones more or less projecting, etc. Certain anomalies in the sutures of the bones, as for example the persistence of the medio-frontal suture, the dispositions of the pterion (point of union of the sutures between the frontal, the temporal, the sphenoid, and the parietal bones), are only important as seriary characters, but there are others which possess some value in the differentiation of races. The Wormian bones, or points of ossification inserted between the bones of the skull, are of the number. One of these bones found between the parietal bones and the occipital, has even received the name of the Inca bone (Fig. [23], A), on account of its very frequent occurrence among Peruvian crania (deformed or not). In fact, it is met with in an imperfect state 20 times in 100 and perfect 5.4 times in 100 among Peruvians, while in Negro crania it is found only 6 times in 100 imperfect, and 1.5 perfect; among Europeans it is still more rarely imperfect, and is hardly ever met with perfect (Anuchin). This peculiarity seems to be a special character of the American race, seeing that among the crania of the Indians of the New World (outside Peruvians) the anomaly in question is found 10 times in 100 imperfect and 1.3 times perfect. Among the Indians of Rio Salado, an affluent of the Gila in Arizona, the frequency of this anomaly is still greater than among Peruvians (5.7 perfect cases against 5.4 in Peru).[64] In the same way, the presence of a suture which divides into two, more or less imperfectly, the malar bone (Fig. [23], B) appears to be a special character of Ainu and Japanese crania; Hilgendorf has even proposed to call the lower portion of the malar bone thus formed os japonicum (Fig. [23], B, a). While the suture is only met with 11 or 12 times in 100 in Mongolian races, and 9 times in 100 in European races according to Ten Kate,[65] it is found from 25 to 40 times in 100 among Japanese according to Doenitz.
It is well understood that in the description of crania the alterations of form produced by all kinds of causes are taken into account. (Such, for example, is the considerable asymmetry or plagiocephaly due to a physiological cause, as the hypertrophy of the capacity of the skull, or its atrophy in the pathological cases of hydrocephaly or microcephaly, and so many other ethnic deformations which will come up for treatment in [Chapter V.], etc.)
The head of the living subject furnishes more numerous characters than the skull, especially if the face be considered with the play of feature. Sometimes an examination of the face suffices to determine the race of the subject.
The measurements of the head are about fifty in number, but they are not all of equal importance. Very few of them, indeed, are really useful.
The chief of the angular measurements is the facial angle; great importance was formerly attached to it when prognathism, or the degree of projection of the maxillary region, was considered as a character of inferiority. In spite of the numerous instruments invented (double square, Harmand’s instrument, Jacquard’s goniometer, etc.), great precision in these measurements is not attainable. The only angle which can be taken with sufficient exactitude, thanks to the facial medium goniometer of Broca, is Cuvier’s angle, formed by a line running either from the glabella or the point between the eyebrows to the interval between the incisor teeth, and by another line starting from the external auditory meatus towards this interval. This angle enables us to estimate the total prognathism and the alveolar prognathism, but the variations which it presents are too slight (3 to 4 degrees), taking race with race, to constitute a distinctive character. Prognathism of the lips, pushed forward to form the prominence of the “muzzle,” which gives so characteristic an expression to the profile of certain Negroes or Australians (Fig. [15]), is not expressed by this measurement, and ordinarily cannot be measured in any way.
Among the measurements of the curve of the head the principal are those of the horizontal circumference with its anterior and posterior portions, the limits of which are found at the supra-auricular point, that is to say, in the depression which is found immediately in front of the spot where the helix of the pinna of the ear is inserted. The value of this measurement has also been exaggerated, it being said that men of well-developed minds have the circumference greater than men without intellectual culture. The comparative observations of Broca made on house-surgeons and attendants of hospitals seem to bear out the assertion; but they have not been confirmed, and stature appears to have a decided relation with the size of the head.