himself.  Besides these exceptional monsters, our bottleheads reach to forty feet, our California whales to forty-four, our hump-backs to fifty, and our razor-backs to sixty or seventy.  True fish generally fall far short of these enormous dimensions, but some of the larger sharks attain almost equal size with the biggest cetaceans.  The common blue shark, with his twenty-five feet of solid rapacity, would have proved a tough antagonist, I venture to believe, for the best bred enaliosaurian that ever munched a lias ammonite.  I would back our modern carcharodon, who grows to forty feet, against any plesiosaurus that ever swam the Jurassic sea.  As for rhinodon, a gigantic shark of the Indian Ocean, he has been actually measured to a length of fifty feet, and is stated often to attain seventy.  I will stake my reputation upon it that he would have cleared the secondary seas of their great saurians in less than a century.  When we come to add to these enormous marine and terrestrial creatures such other examples as the great snakes, the gigantic cuttle-fish, the grampuses, and manatees, and sea-lions, and sunfish, I am quite prepared fearlessly to challenge any other age that ever existed to enter the lists against our own for colossal forms of animal life.

Again, it is a point worth noting that a great many of the very big animals which people have in their minds when they talk vaguely about everything having been so very much bigger ‘in those days’ have become extinct within a very late period, and are often, from the geological point of view, quite recent.

For example, there is our friend the mammoth.  I suppose no animal is more frequently present to the mind of the non-geological speaker, when he talks indefinitely about the great extinct monsters, than the familiar figure of that huge-tusked, hairy northern elephant.  Yet the mammoth, chronologically speaking, is but a thing of yesterday.  He was hunted here in England by men whose descendants are probably still living—­at least so Professor Boyd Dawkins solemnly assures us; while in Siberia his frozen body, flesh and all, is found so very fresh that the wolves devour it, without raising any unnecessary question as to its fitness for lupine food.  The Glacial Epoch is the yesterday of geological time, and it was the Glacial Epoch that finally killed off the last mammoth.  Then, again, there is his neighbour, the mastodon.  That big tertiary proboscidean did not live quite long enough, it is true, to be hunted by the cavemen of the Pleistocene age, but he survived at any rate as long as the Pliocene—­our day before yesterday—­and he often fell very likely before the fire-split flint weapons of the Abbe Bourgeois’ Miocene men.  The period that separates him from our own day is as nothing compared with the vast and immeasurable interval that separates him from the huge marine saurians of the Jurassic world.  To compare the relative lapses of time with human chronology, the mastodon stands to our own fauna as Beau Brummel stands to the modern masher, while the saurians stand to it as the Egyptian and Assyrian warriors stand to Lord Wolseley and the followers of the Mahdi.