in exterminating inferior forms is shown by the fate of the carnivorous marsupials of South America (allied to _Thylacinus_), which were the predatory fauna of that region, until in the Pliocene, North and South America having become united by continuous land, cats and dogs came in from the northern continent and put an end to them; and also by the fate of the creodonts, which in the Oligocene seem everywhere to have been exterminated by the new carnivores. In both cases the beaten competitors were very inferior in the size and complexity of their brains; and if Man has succeeded in the struggle for life against the same foes, in spite of his inferior bodily adaptation, it is probably due to his very superior brains. This may also be the reason why modern Man (_Homo sapiens!_), wandering everywhere over the world, has everywhere exterminated such experiments in human nature as Pithecanthropus, Eoanthropus, and Neanderthalensis; as others are soon to follow them into the Hades of extinct species. These few pages give a ridiculously faint sketch of the animal world amidst which our remote ancestors began their career. But it may serve to indicate that there was always plenty to eat if you could kill it, and plenty of rivals who wanted their share. After the disappearance of the dinosaurs at the close of the Cretaceous period, the mammalia, already numerous, developed rapidly, and spread in ever multiplying numbers and diverging shapes over the whole area of the land. We may take it that from the Middle Eocene (at least) onwards the earth has always been as full of wild beasts as it would hold. To understand what it was like in the Middle Oligocene, one should read the adventures of hunters in South Africa seventy or eighty years ago (their verisimilitude is vouched for by Livingstone),[27] before a gun in the hands of every Kaffir had begun to thin the vast herds that then covered the whole landscape, and in whose numbers the wild hunters and the lions could make no appreciable diminution. The little Bushmen regarded themselves and the lions as joint owners and masters of all the game. The masters fought one another, indeed; but there was no necessity to fight, for there was more than enough for both: lions were then sometimes met in gangs of ten or a dozen. Game throughout the Cainozoic ages was abundant and of all sizes: many small, many middle-sized and some prodigious. Even in the Eocene, some of the Amblypoda (_Dinoceras_, Am.) and of the Barypoda (_Arsinotherium_, Af.) were as big as rhinoceroses; in the Oligocene, Titanotheres not much smaller than elephants; in South America, in Miocene and Pliocene times, the Toxodonts; in the Pleistocene, Ground-sloths of huge bulk, and Glyptodonts. Of Families still represented amongst living animals, dinotheres and mastodons occur in the Miocene; and elephant, rhinoceros, hippopotamus, giraffe have abounded from the Pliocene to recent times, in many species, over most of Africa and the northern