It is not necessary to conclude from these or other diversities in skull forms that the American race is a conglomerate of other and varied stocks. As I have pointed out elsewhere, the shape of the skull is not a fixed element in human anatomy, and children of the same mother may differ in this respect.[36] A special feature in American skulls is the presence of the epactal bone, or _os Incæ_, in the occiput. It is found in a complete or incomplete condition in 3.86 per cent. of the skulls throughout the continent, and in particular localities much more frequently; among the ancient Peruvians for example in 6.08 per cent., and among the former inhabitants of the Gila valley in 6.81 per cent. This is far more frequently than in other races, the highest being the negro, which offers 2.65 per cent., while the Europeans yield but 1.19.[37] The presence of the bone is due to a persistence of the transverse occipital suture, which is usually closed in fetal life. Hence it is a sign of arrested development, and indicative of an inferior race. The majority of the Americans have a tendency to meso- or brachycephaly, but in certain families, as the Eskimos in the extreme north and the Tapuyas in Brazil, the skulls are usually decidedly long. In other instances there is a remarkable difference in members of the same tribe and even of the same household. Thus among the Yumas there are some with as low an index as 68, while the majority are above 80, and among the dolichocephalic Eskimos we occasionally find an almost globular skull. So far as can be learned, these variations appear in persons of pure blood. Often the crania differ in no wise from those of the European. Dr. Hensell, for instance, says that the skulls of pure-blood Coroados of Brazil, which he examined, corresponded in all points to those of the average German.[38] The average cubical capacity of the American skull falls below that of the white, and rises above that of the black race. Taking both sexes, the Parisians of to-day have a cranial capacity of 1448 cubic centimetres; the Negroes 1344 c. c.; the American Indians 1376.[39] But single examples of Indian skulls have yielded the extraordinary capacity of 1747, 1825, and even 1920 cub. cent. which are not exceeded in any other race.[40] The hue of the skin is generally said to be reddish, or coppery, or cinnamon color, or burnt coffee color. It is brown of various shades, with an undertone of red. Individuals or tribes vary from the prevailing hue, but not with reference to climate. The Kolosch of the northwest coast are very light colored; but not more so than the Yurucares of the Bolivian Andes. The darkest are far from black, and the lightest by no means white.