For few people ever really remember how very many big animals we still possess. We have the Indian and the African elephant, the hippopotamus, the various rhinoceroses, the walrus, the giraffe, the elk, the bison, the musk ox, the dromedary, and the camel. Big marine animals are generally in all ages bigger than their biggest terrestrial rivals, and most people lump all our big existing cetaceans under the common and ridiculous title of whales, which makes this vast and varied assortment of gigantic species seem all reducible to a common form. As a matter of fact, however, there are several dozen colossal marine animals now sporting and spouting in all oceans, as distinct from one another as the camel is from the ox, or the elephant from the hippopotamus. Our New Zealand Berardius easily beats the ichthyosaurus; our sperm whale is more than a match for any Jurassic European deinosaur; our rorqual, one hundred feet long, just equals the dimensions of the gigantic American Atlantosaurus 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 Abbé 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.

Once more, take the gigantic moa of New Zealand, that enormous bird who was to the ostrich as the giraffe is to the antelope; a monstrous emu, as far surpassing the ostriches of to-day as the ostriches surpass all the other fowls of the air. Yet the moa, though now extinct, is in the strictest sense quite modern, a contemporary very likely of Queen Elizabeth or Queen Anne, exterminated by the Maoris only a very little time before the first white settlements in the great southern archipelago. It is even doubtful whether the moa did not live down to the days of the earliest colonists, for remains of Maori encampments are still discovered, with the ashes of the fireplace even now unscattered, and the close-gnawed bones of the gigantic bird lying in the very spot where the natives left them after their destructive feasts. So, too, with the big sharks. Our modern carcharodon, who runs (as I have before noted) to forty feet in length, is a very respectable monster indeed, as times go; and his huge snapping teeth, which measure nearly two inches long by one and a half broad, would disdain to make two bites of the able-bodied British seaman. But the naturalists of the 'Challenger' expedition dredged up in numbers from the ooze of the Pacific similar teeth, five inches long by four wide, so that the sharks to which they originally belonged must, by parity of reasoning, have measured nearly a hundred feet in length. This, no doubt, beats our biggest existing shark, the rhinodon, by some thirty feet. Still, the ooze of the Pacific is a quite recent or almost modern deposit, which is even now being accumulated on the sea bottom, and there would be really nothing astonishing in the discovery that some representatives of these colossal carcharodons are to this day swimming about at their lordly leisure among the coral reefs of the South Sea Islands. That very cautious naturalist, Dr. Günther, of the British Museum, contents himself indeed by merely saying: 'As we have no record of living individuals of that bulk having been observed, the gigantic species to which these teeth belonged must probably have become extinct within a comparatively recent period.'

If these things are so, the question naturally suggests itself: Why should certain types of animals have attained their greatest size at certain different epochs, and been replaced at others by equally big animals of wholly unlike sorts? The answer, I believe, is simply this: Because there is not room and food in the world at any one time for more than a certain relatively small number of gigantic species. Each great group of animals has had successively its rise, its zenith, its decadence, and its dotage; each at the period of its highest development has produced a considerable number of colossal forms; each has been supplanted in due time by higher groups of totally different structure, which have killed off their predecessors, not indeed by actual stress of battle, but by irresistible competition for food and prey. The great saurians were thus succeeded by the great mammals, just as the great mammals are themselves in turn being ousted, from the land at least, by the human species.

Let us look briefly at the succession of big animals in the world, so far as we can follow it from the mutilated and fragmentary record of the geological remains.

The very earliest existing fossils would lead us to believe what is otherwise quite probable, that life on our planet began with very small forms—that it passed at first through a baby stage. The animals of the Cambrian period are almost all small mollusks, star-fishes, sponges, and other simple, primitive types of life. There were as yet no vertebrates of any sort, not even fishes, far less amphibians, reptiles, birds, or mammals. The veritable giants of the Cambrian world were the crustaceans, and especially the trilobites, which, nevertheless, hardly exceeded in size a good big modern lobster. The biggest trilobite is some two feet long; and though we cannot by any means say that this was really the largest form of animal life then existing, owing to the extremely broken nature of the geological record, we have at least no evidence that anything bigger as yet moved upon the face of the waters. The trilobites, which were a sort of triple-tailed crabs (to speak very popularly), began in the Cambrian Epoch, attained their culminating point in the Silurian, waned in the Devonian, and died out utterly in the Carboniferous seas.

It is in the second great epoch, the Silurian, that the cuttle-fish tribe, still fairly represented by the nautilus, the argonaut, the squid, and the octopus, first began to make their appearance upon this or any other stage. The cuttle-fishes are among the most developed of invertebrate animals; they are rapid swimmers; they have large and powerful eyes; and they can easily enfold their prey (teste Victor Hugo) in their long and slimy sucker-clad arms. With these natural advantages to back them up, it is not surprising that the cuttle family rapidly made their mark in the world. They were by far the most advanced thinkers and actors of their own age, and they rose almost at once to be the dominant creatures of the primæval ocean in which they swam. There were as yet no saurians or whales to dispute the dominion with these rapacious cephalopods, and so the cuttle family had things for the time all their own way. Before the end of the Silurian Epoch, according to that accurate census-taker, M. Barrande, they had blossomed forth into no less than 1,622 distinct species. For a single family to develop so enormous a variety of separate forms, all presumably derived from a single common ancestor, argues, of course, an immense success in life; and it also argues a vast lapse of time during which the different species were gradually demarcated from one another.

Some of the ammonites, which belonged to this cuttle-fish group, soon attained a very considerable size; but a shell known as the orthoceras (I wish my subject didn't compel me to use such very long words, but I am not personally answerable, thank heaven, for the vagaries of modern scientific nomenclature) grew to a bigger size than that of any other fossil mollusk, sometimes measuring as much as six feet in total length. At what date the gigantic cuttles of the present day first began to make their appearance it would be hard to say, for their shell-less bodies are so soft that they could leave hardly anything behind in a fossil state; but the largest known cuttle, measured by Mr. Gabriel, of Newfoundland, was eighty feet in length, including the long arms.

These cuttles are the only invertebrates at all in the running so far as colossal size is concerned, and it will be observed that here the largest modern specimen immeasurably beats the largest fossil form of the same type. I do not say that there were not fossil forms quite as big as the gigantic calamaries of our own time—on the contrary, I believe there were; but if we go by the record alone we must confess that, in the matter of invertebrates at least, the balance of size is all in favour of our own period.

The vertebrates first make their appearance, in the shape of fishes, towards the close of the Silurian period, the second of the great geological epochs. The earliest fish appear to have been small, elongated, eel-like creatures, closely resembling the lampreys in structure; but they rapidly developed in size and variety, and soon became the ruling race in the waters of the ocean, where they maintained their supremacy till the rise of the great secondary saurians. Even then, in spite of the severe competition thus introduced, and still later, in spite of the struggle for life against the huge modern cetaceans (the true monarchs of the recent seas), the sharks continued to hold their own as producers of gigantic forms; and at the present day their largest types probably rank second only to the whales in the whole range of animated nature. There seems no reason to doubt that modern fish, as a whole, quite equal in size the piscine fauna of any previous geological age.

It is somewhat different with the next great vertebrate group, the amphibians, represented in our own world only by the frogs, the toads, the newts, and the axolotls. Here we must certainly with shame confess that the amphibians of old greatly surpassed their degenerate descendants in our modern waters. The Japanese salamander, by far the biggest among our existing newts, never exceeds a yard in length from snout to tail; whereas some of the labyrinthodonts (forgive me once more) of the Carboniferous Epoch must have reached at least seven or eight feet from stem to stern. But the reason of this falling off is not far to seek. When the adventurous newts and frogs of that remote period first dropped their gills and hopped about inquiringly on the dry land, under the shadow of the ancient tree-ferns and club-mosses, they were the only terrestrial vertebrates then existing, and they had the field (or, rather, the forest) all to themselves. For a while, therefore, like all dominant races for the time being, they blossomed forth at their ease into relatively gigantic forms. Frogs as big as donkeys, and efts as long as crocodiles, luxuriated to their hearts' content in the marshy lowlands, and lorded it freely over the small creatures which they found in undisturbed possession of the Carboniferous isles. But as ages passed away, and new improvements were slowly invented and patented by survival of the fittest in the offices of nature, their own more advanced and developed descendants, the reptiles and mammals, got the upper hand with them, and soon lived them down in the struggle for life, so that this essentially intermediate form is now almost entirely restricted to its one adapted seat, the pools and ditches that dry up in summer.

The reptiles, again, are a class in which the biggest modern forms are simply nowhere beside the gigantic extinct species. First appearing on the earth at the very close of the vast primary periods—in the Permian age—they attained in secondary times the most colossal proportions, and have certainly never since been exceeded in size by any later forms of life in whatever direction. But one must remember that during the heyday of the great saurians, there were as yet no birds and no mammals. The place now filled in the ocean by the whales and grampuses, as well as the place now filled in the great continents by the elephants, the rhinoceroses, the hippopotami, and the other big quadrupeds, was then filled exclusively by huge reptiles, of the sort rendered familiar to us all by the restored effigies on the little island in the Crystal Palace grounds. Every dog has his day, and the reptiles had their day in the secondary period. The forms into which they developed were certainly every whit as large as any ever seen on the surface of this planet, but not, as I have already shown, appreciably larger than those of the biggest cetaceans known to science in our own time.

During the very period, however, when enaliosaurians and pterodactyls were playing such pranks before high heaven as might have made contemporary angels weep, if they took any notice of saurian morality, a small race of unobserved little prowlers was growing up in the dense shades of the neighbouring forests which was destined at last to oust the huge reptiles from their empire over earth, and to become in the fulness of time the exclusively dominant type of the whole planet. In the trias we get the first remains of mammalian life in the shape of tiny rat-like animals, marsupial in type, and closely related to the banded ant-eaters of New South Wales at the present day. Throughout the long lapse of the secondary ages, across the lias, the oolite, the wealden, and the chalk, we find the mammalian race slowly developing into opossums and kangaroos, such as still inhabit the isolated and antiquated continent of Australia. Gathering strength all the time for the coming contest, increasing constantly in size of brain and keenness of intelligence, the true mammals were able at last, towards the close of the secondary ages, to enter the lists boldly against the gigantic saurians. With the dawn of the tertiary period, the reign of the reptiles begins to wane, and the reign of the mammals to set in at last in real earnest. In place of the ichthyosaurs we get the huge cetaceans; in place of the deinosaurs we get the mammoth and the mastodon; in place of the dominant reptile groups we get the first precursors of man himself.

The history of the great birds has been somewhat more singular. Unlike the other main vertebrate classes, the birds (as if on purpose to contradict the proverb) seem never yet to have had their day. Unfortunately for them, or at least for their chance of producing colossal species, their evolution went on side by side, apparently, with that of the still more intelligent and more powerful mammals; so that, wherever the mammalian type had once firmly established itself, the birds were compelled to limit their aspirations to a very modest and humble standard. Terrestrial mammals, however, cannot cross the sea; so in isolated regions, such as New Zealand and Madagascar, the birds had things all their own way. In New Zealand, there are no indigenous quadrupeds at all; and there the huge moa attained to dimensions almost equalling those of the giraffe. In Madagascar, the mammalian life was small and of low grade, so the gigantic æpyornis became the very biggest of all known birds. At the same time, these big species acquired their immense size at the cost of the distinctive birdlike habit of flight. A flying moa is almost an impossible conception; even the ostriches compete practically with the zebras and antelopes rather than with the eagles, the condors, or the albatrosses. In like manner, when a pigeon found its way to Mauritius, it developed into the practically wingless dodo; while in the northern penguins, on their icy perches, the fore limbs have been gradually modified into swimming organs, exactly analogous to the flippers of the seal.

Are the great animals now passing away and leaving no representatives of their greatness to future ages? On land at least that is very probable. Man, diminutive man, who, if he walked on all fours, would be no bigger than a silly sheep, and who only partially disguises his native smallness by his acquired habit of walking erect on what ought to be his hind legs—man has upset the whole balanced economy of nature, and is everywhere expelling and exterminating before him the great herbivores, his predecessors. He needs for his corn and his bananas the fruitful plains which were once laid down in prairie or scrubwood. Hence it seems not unlikely that the elephant, the hippopotamus, the rhinoceros, and the buffalo must go. But we are still a long way off from that final consummation, even on dry land; while as for the water, it appears highly probable that there are as good fish still in the sea as ever came out of it. Whether man himself, now become the sole dominant animal of our poor old planet, will ever develop into Titanic proportions, seems far more problematical. The race is now no longer to the swift, nor the battle to the strong. Brain counts for more than muscle, and mind has gained the final victory over mere matter. Goliath of Gath has shrunk into insignificance before the Gatling gun; as in the fairy tales of old, it is cunning little Jack with his clever devices who wins the day against the heavy, clumsy, muddle-headed giants. Nowadays it is our 'Minotaurs' and 'Warriors' that are the real leviathans and behemoths of the great deep; our Krupps and Armstrongs are the fire-breathing krakens of the latter-day seas. Instead of developing individually into huge proportions, the human race tends rather to aggregate into vast empires, which compete with one another by means of huge armaments, and invent mitrailleuses and torpedos of incredible ferocity for their mutual destruction. The dragons of the prime that tare each other in their slime have yielded place to eighty-ton guns and armour-plated turret-ships. Those are the genuine lineal representatives on our modern seas of the secondary saurians. Let us hope that some coming geologist of the dim future, finding the fossil remains of the sunken 'Captain,' or the plated scales of the 'Comte de Grasse,' firmly embedded in the upheaved ooze of the existing Atlantic, may shake his head in solemn deprecation at the horrid sight, and thank heaven that such hideous carnivorous creatures no longer exist in his own day.