The shape as well as the size of the skull affords another test of race which is often appealed to. The main distinction taken is between dolichocephalic and brachycephalic, or long and broad skulls. Here also we must look at general averages rather than at individuals, for there is often considerable variation within the same race, especially among the mesocephalic, or medium between the two extremes, which is generally the prevalent form where there has been much intermixture of races. But if we take widely different types there can be no doubt that the long or broad skull is a characteristic and persistent feature. The formation of the jaws and teeth affords another important test. Some races are what is called prognathous, that is, the jaws project, and the teeth are set in sockets sloping outwards, so that the lower part of the face approximates to the form of a muzzle; others are orthognathous, or have the jaws and teeth vertical. And the form of the chin seems to be wonderfully correlated with the general character and energy of the race. It is hard to say why, but as a matter of fact a weak chin generally denotes a weak, and a strong chin a strong, race or individual. Thus the chimpanzee and other apes have no chin, the negro and lower races generally have chins weak and receding. The races who, like the Iberians, have been conquered or driven from plains to mountains, have had poor chins; while their successive conquerors, of Aryan race,--Celts, Romans, Teutons, and Scandinavians,--might almost be classified by the prominence and solidity of this feature of the face. Stature is another very persistent feature. The pygmy races of Equatorial Africa described by Stanley have remained the same since the early records of Egypt, while the pure Aryan races of the north temperate zone, Gauls, Germans, and Scandinavians, have from the first dawn of history amazed the shorter races of the south by their tall stature, huge limbs, blue eyes, and yellow hair. Here and there isolated tall races may be found where the race has become thoroughly acclimatized to a suitable environment, as among some negro tribes, and the Araucanian Indians of Patagonia; but as a rule the inferior races are short, the bulk of the civilized races of the world of intermediate stature, and the great conquering races of the north temperate zone decidedly tall. Other tests are afforded by the shape of the eye-orbits and nasal bones, and other characters, all of which agree, in the words of Isaac Taylor in his _Origin of the Aryans_, in "exhibiting two extreme types--the African with long heads, long orbits, and flat hair; and the Mongolian with round heads, round orbits, and round hair. The European type is intermediate, the head, the orbit, and the hair being oval. In the East of Europe we find an approximation to the Asiatic type; in the South of Europe to the African."