[55] Havelock Ellis, Man and Woman, p. 223. London, 1897.
[56] These characters, in conjunction with several others—the small development of the lower jaw-bone, the frontal sinuses poorly developed, the much greater development of the cranial vault proportionately to its base, the persistence of the frontal and parietal bumps—make the feminine skull approximate to the infantile form. See the works of Broca, Manouvrier, and also Rabentisch, Der Weiberschädel, Morpholog. Arb., Schwalbe, 1892, vol. ii., p. 207; and H. Ellis, loc. cit., p. 72.
[57] H. Ellis, loc. cit., p. 89 and onwards; L. Manouvrier, article “Cerveau” in the Dict. de Physiol. de Ch. Richet, vol. ii., part 8, Paris, 1897.
[58] According to the quinary nomenclature adopted in many countries of Europe, the indices are grouped by series of five: dolichocephalic from 70 to 74.9; mesocephalic from 75 to 79.9; brachycephalic from 80 to 84.9; hyper-brachycephalic from 85 to 89.9. The two systems might be combined with advantage, as I proposed ten years ago, under the following nomenclature, which I have adopted in this work:—Cephalic index of the skull: From 69.9 and under, hyper-dolichocephalic; from 70 to 74.9, dolichocephalic; from 75 to 77.7, sub-dolichocephalic; from 77.7 to 79.9, mesocephalic; from 80 to 83.2, sub-brachycephalic; from 83.3 to 84.9, brachycephalic; from 85 to 85.9, hyper-brachycephalic; from 90 and upwards, ultra-brachycephalic.
[59] Skulls may also be grouped by sections (for instance, ascending to the quinary nomenclature of the cephalic index) to see what is the proportional part of each of these sections. Thus if we take a series of 10 skulls having the following indices, 75, 77, 78, 80, 80, 81, 81, 81, 82, 84, their average index will be expressed by the figure 80 (the sum of the indices divided by the number of skulls), while the most frequent mean index will be 81. Further, the series should be considered as not very homogeneous, for it comprises 1 dolichocephalic, 1 sub-dolichocephalic, 1 mesocephalic, 6 sub-brachycephalic, and 1 brachycephalic.
[60] It is rather a line than a plane; the cranium always being asymmetrical, we cannot make a horizontal plane pass exactly through the borders of the two orbits and the two auditory meatus.
[61] Broca, “Recherches sur l’indice orbitaire,” Rev. Anthro., p. 577, Paris, 1875.
[62] C.E., an abbreviation which is met with in other tables for Crania ethnica of De Quatrefages and Hamy, Paris, 1882.
[63] L. Weiss, Beitr. Anat. der Orbita, part 3, p. 25, Tübingen, 1890.
[64] Ten Kate, L’Anthropologie, 1894, p. 617.