All we can say with any certainty is, that if the Darwinian theory of evolution applies to man, as it does to all other animals, and specially to man's closest kindred, the other quadrumana, the common ancestor must be sought very much further back, in the Eocene, which inaugurated the reign of placental mammalia, and in which the primitive types of so many of the later mammals have been found. Nor will this appear incredible when we consider that man's cousins, the apes and monkeys, first appear in the Miocene, or even earlier in the Eocene, and become plentiful in the later Pliocene, and that even anthropoid apes, and one of them, the Hylobates, scarcely if at all distinguishable from the Gibbon of the present day, have been found at Sansan and other Miocene deposits in the south of France, at OEningen in Switzerland, and Pikermi in Greece; while if Professor Ameghino's discoveries are to be credited, anthropoids already existed in the Eocene, and their development may be traced from the oldest Eocene forms. CHAPTER XII. RACES OF MANKIND. Monogeny or Polygeny--Darwin--Existing Races--Colour--Hair--Skulls and Brains--Dolichocephali and Brachycephali--Jaws and Teeth--Stature--Other Tests--Isaac Taylor--Prehistoric Types in Europe--Huxley's Classification--Language no Test of Race--Egyptian Monuments--- Human and Animal Races unchanged for 6000 years--Neolithic Races--Palæolithic--Different Races of Man as far back as we can trace--Types of Canstadt, Cro-Magnon, and Furfooz--Oldest Races Dolichocephalic--Skulls of Neanderthal and Spy--Simian Characters--Objections--Evidence confined to Europe--American Man--Calaveras Skull--Tertiary Man--Skull of Castelnedolo--Leaves Monogeny or Polygeny an open Question--Arguments on each side--Old Arguments from the Bible and Philology exploded--What Darwinian Theory requires--Animal Types traced up to the Eocene--Secondary Origins--Dog and Horse--Fertility of Races--Question of Hybridity--Application to Man--Difference of Constitutions--Negro and White--Bearing on Question of Migration--Apes and Monkeys--Question of Original Locality of Man--Asiatic Theory--Eur-African--American--Arctic--None based on sufficient Evidence--- Mere Speculations--Conclusion--Summary of Evidence as to Human Origins. The immense antiquity of man upon earth having been established, other questions of great interest present themselves as to the origin of the race. These questions, however, no longer depend on positive facts of observation, like the discovery of palæolithic remains in definite geological deposits, but on inference and conjecture from these and other observed facts, most of which are of comparatively recent date and hardly extend beyond the historical period.