Normal Forms of the Cranium
We are indebted to Sergi for an exact knowledge of the normal forms of the cranium. Such forms are racial characteristics and are invariable, as Sergi has succeeded in proving by a comparison of the most ancient forms of the cranium with recent forms. Accordingly this authority takes the cranial formation as the basis for his classification of races. We have no direct interest, so far as concerns the special scope of our own science, in the value of this theory of classification—a theory, by the way, already divined, although very imperfectly and under a different form, by French and German anthropologists. Sergi's studies of cranial forms interest us solely as a diagnostic test of normality as compared with abnormality. For it is due to these researches that certain forms that used to be considered pathological, have come to be recognised as normal.
The normal forms of the cranium may be grouped, according to Sergi, under nine primary varieties, each of which includes sub-varieties.
These nine varieties are named as follows:
I. Ellipsoid; II. Ovoid; III. Pentagonoid; IV. Rhomboid; V. Beloid; VI. Cuboid; VII. Sphenoid; VIII. Spheroid; IX. Platycephalic.
Fig. 57.—Ellipsoides depressus cranium.
I. Ellipsoid (Fig. 58).—This form is recognised by inspecting the cranium according to the vertical norm (see in the chapter on Technique the method of cranioscopy).
The cranial contour recalls an ellipse in which no trace of the nodules remains, and in which the occiput is not in the least flattened; while the anterior half of the cranium closely corresponds to the posterior half.
The sub-varieties are differentiated by their greater breadth and length, by the form and protrusion of the occiput, and also by the height of the cranium measured vertically.
Fig. 58.—Ellipsoid cranium.
Fig. 59.—Ovoid cranium.
Accordingly, the sub-varieties have a binominal nomenclature indicating, in addition to the fundamental characteristic (variety) the qualitative characteristic of the sub-variety (e.g., ellipsoids depressus; compare Fig. 57, showing a cranium seen laterally).
II. Ovoid.—This form of cranium, seen from above, is that of an ovoid, with the broader portion corresponding to the parietal bones, at the point where the characteristic embryonal nodules are situated. The protrusions of the parietal bones are apparent (swellings) but not angular (nodules). The occiput protrudes and is broad (Fig. 59).
Fig. 60.—Pentagonoid cranium.
Fig. 61.—Rhomboid cranium.
III. Pentagonoid.—In this form, persistent traces of the five primitive embryonal nodules are still plainly visible, giving the contour of the cranium, when seen vertically, the appearance of a pentagon. The protuberances, however, are quite smooth and not pointed, as in the embryonal cranium.
Fig. 62.—Beloid cranium.
IV. Rhomboid.—This form is similar to the pentagonoid, excepting that the parietal breadth is much more notable in proportion to the forehead, which is much narrowed and has lost its nodules.
Fig. 63.—Ovoids (classified by Sergi).
Fig. 64.—Pentagonoides acutus (Sergi's collection).
Fig. 65.—Beloides lybicus (classified by Sergi).
Fig. 66.—Platycephalus orbicularis (classified by Sergi).
Fig. 67.—Platycephalus ovoidalis (classified by Sergi).
Fig. 68.—Spheroidal cranium, vertical norm (Sergi's collection).
V. Beloid.—The beloid, or arrow-head cranium is like the ovoid with the occiput more flattened, so that the widest portion is further back than in the ovoid; toward the front it becomes narrower, constituting altogether an admirably shaped type of head.
Fig. 69.—Cuboid cranium.
VI. Cuboid.—This form is most clearly perceived when the cranium is seen either sidewise or from the rear. Not only the face, but the lateral and occipital walls as well are flattened; so also is the forehead, which in general is quite vertical.
VII. Sphenoid (cuneiform).—The broadening between the two parietal bones is usually far back and very evident, while the cranium narrows toward the front. The occiput is flattened.
Fig. 70.—Sphenoid cranium.
VIII. Spheroid.—Seen vertically, it presents the appearance of a very broad ellipse; all the curves tend to become spherical. The forehead, however, is not notably vertical.
IX. Platycephalic.—The fundamental characteristic of this type of cranium is that it is flattened on top, or rather, since such flattening cannot be absolute, the arch of its vault is a segment of a circle of very large diameter (Sergi), with the result that this cranium has the appearance of being very low vertically and very broad laterally. When seen vertically it may present a wide variety of contours, ellipsoid, ovoid, pentagonoid, etc., but its distinguishing characteristic remains that of the flattened vault.
Fig. 71.—Spheroid cranium.
Sub-varieties.—Sphenoids trapezoids, or trapezoid cranium. Observed from the vertical norm, this form appears as a variety of the sphenoid; and when seen laterally it is characterised by the lines of its contour forming a trapezium. Starting from the vertex of the cranium one line slants toward the forehead and another toward the occiput, which is very massive. In the figure given below, the quadrangle drawn in solid lines serves to indicate the correct position of the cranium, while the trapezium formed of dotted lines gives us its characteristic form.
Fig. 72.—Trapezoid cranium.
Among the forms described by Sergi, are several which were formerly held to be abnormal, such, for instance, as the platycephalic cranium and the pentagonoid. Similarly, when the surfaces of the cranium showed a tendency toward flatness, or when there were cranial protuberances, even though these were destined to disappear, they were regarded as malformations. Before this high authority offered us his guidance, there were certain forms, frequently encountered, that it was difficult to define, for example, the trapezoid cranium, which often presents a notable vertico-occipital flattening, with the vertex notably higher than the forehead.
There are also certain forms of cranium having the frontal region more restricted than the parietal region, or slanting down from a much elevated vertex, which have been proved to be normal forms; while still another error previously made was that of trying to judge the forehead on the criterion of a single model, deviations from which were much too readily relegated to the category of abnormalities. The most regular and beautiful forms, and the ones that are commonest in our racial stocks are the ellipsoid, ovoid and sphenoid. In my work on the women of Latium, precisely one of the points that I noted was the frequent occurrence of certain sub-varieties of the ellipsoid and the sphenoid.
In order to recognise the forms of the cranium, a certain training is necessary which each one must acquire for himself. Observations of the cranium will make it easier to judge of the form in relation to the head, at least, when the latter is not too much hidden by the hair, as often happens in the case of young children.
A knowledge of the normal forms of the cranium will also guide us in our judgment of many abnormal forms, which very often present the appearance of exaggerations of normal types.
Thus, for example, the acrocephalic cranium (much raised in the parieto-lambdoideal region and sloping forward toward the brow, while the occipito-lambdoideal region is flattened) recalls the trapezoid; and the clinocephalic cranium (in which the coronal suture forms a slight girdle-like indenture and divides the contour of the cranium, when observed along the vertical norm, in two curves, a lesser anterior and a greater posterior curve, resembling a figure of 8) recalls certain varieties of ovoid cranium described by Sergi. This brings us to a principle that is very interesting to establish, namely, that frequently anomalies represent exaggerations of the racial or family type.