Page:Darwinism by Alfred Wallace 1889.djvu/413

 reason for the extinction has yet been given. Besides the characters I have mentioned, there are many others in the skeleton, skull, teeth, and brain of the forty or more intermediate species, which show that the transition from the Eocene Eohippus to the modern Equus has taken place in the order indicated" (see Fig. 33).

Well may Professor Huxley say that this is demonstrative evidence of evolution; the doctrine resting upon exactly as secure a foundation as did the Copernican theory of the motions of the heavenly bodies at the time of its promulgation. Both have the same basis—the coincidence of the observed facts with the theoretical requirements.

[[c|Development of Deer's Horns.}}

Another clear and unmistakable proof of evolution is afforded by one of the highest and latest developed tribes of mammals—the true deer. These differ from all other ruminants in possessing solid deciduous horns which are always more or less branched. They first appear in the Middle Miocene formation, and continue down to our time; and their development has been carefully traced by Professor Boyd Dawkins, who thus summarises his results:—

"In the middle stage of the Miocene the cervine antler consists merely of a simple forked crown (as in Cervus dicroceros), which increases in size in the Upper Miocene, although it still remains small and erect, like that of the roe. In Cervus Matheroni it measures 11·4 inches, and throws off not more than four tines, all small. The deer living in Auvergne in the succeeding or Pliocene age, present us with another stage in the history of antler development. There, for the first time, we see antlers of the Axis and Rusa type, larger and longer, and more branching than any antlers were before, and possessing three or more well-developed tines. Deer of this type abounded in Pliocene Europe. They belong to the Oriental division of the Cervidae, and their presence in Europe confirms the evidence of the flora, brought forward by the Comte de Saporta, that the Pliocene climate was warm. They have probably disappeared from Europe in consequence