all the creatures that ever dwelt upon the earth this was one of the most terrible. It had Herculean strength, indomitable fierceness, insatiable voracity, and faculties enabling it to wage deadly war with its compeers. The Iguanodon is supposed to have been an herbivorous animal; judging from the structure of its teeth, claws, and body, it must have been comparatively innocent; and judging from its legs and feet, it was a land animal, and not amphibious. It was of colossal size, being about 27 yards in length, and of proportionate height. The aerial reptiles included the numerous family of the Ptero-dactyl. They were the

most singular creatures that ever existed. In form and structure they resembled the modern bat. Dr. Buckland says, "From their wings projected fingers, terminated by long hooks, like the curved claw in the thumb of a bat. These must have formed a powerful claw, wherewith the animal was enabled to creep, or climb, or suspend itself from trees. It is probable, also, that it had the power of swimming, which is so common to reptiles." The head of this winged Saurian was of an enormous size, resembling that of a lizard; its neck was long, and its body was covered with glittering scales instead of feathers. Its wing hands were connected with its body and hind legs, and the fingers with each other by a sort of web, which was generally held in an upright position. Geologians tell us that it could walk on the earth like a bird, but that it could fly or swim much better than it could walk. It might be seen occasionally hovering high in the air, over sea or land, swooping down betimes, with terrific force, on some devoted animal, or darting beneath the waters in search of prey. Residing chiefly on land, its fossil remains are not so

common, and consequently, not so frequently met with as those of its marine and amphibious comrades. And then it must be understood that the three classes of reptiles came into being in the order mentioned by Moses. Aquatic reptiles were created and lived in the Triassic seas; while during the Oolitic era, terrestrial, then winged, Saurians were brought forth. And nearly all of them became extinct during the Cretaceous system, or the chalk formation. Sea-lizards are now reduced to one genus, called the Mosa-saurus, so called because the first specimen was found near the banks of the river Mosa. It must not be supposed that the destruction of these reptiles was suddenly effected by universal deluge, conflagration, or earthquakes. It must rather be ascribed to that gradual development which rendered the earth unfit for their existence, being now more suitable for others of a higher organization. During this period the condition of the earth had considerably improved on the preceding eras. The sea, dry land, and air had all teemed with inhabitants. The sea then ebbed and flowed; the sun rose and set; the moon and stars shone out by night then, as now. In the air those winged Saurians flew; on the land stalked forth the ponderous crocodile for purposes of prey. In the sea hosts of marine lizards in "fell encounter met," while others lingered near the shore to satiate themselves on smaller fish. To get a view of the scenes that then transpired, let us fancy ourselves on some projecting rock, looking seaward; the first object of attention might be some crocodilian reptile, slowly moving to the water's edge, then darting forwards, overtaking and devouring the finny tribes that swarmed about the shallows. Out a little

distance in the ocean we may recognise the dim outline of large reptilian forms, above the surface of the waters, resting or sporting in their native element. Others are darting swiftly through the waters, capturing birds and fishes. Turning landward, we see creeping crocodiles swarm forth abundantly; or, having satisfied themselves with prey, they sleep half buried in the muddy shore or verdant plain. Now comes forth that mighty megalosaurus in search of food. Scenting prey, he springeth forth, and with one stroke of his powerful foot and terrible claws the teleosaur is struck dead and instantly devoured. Again and again this process is repeated, until, gorged with victims, he returns leisurely to his lair, or stretching himself upon the verdant shore, he basks in the warmth of a tropical sun. Geologians tell us that during the secondary period the ocean that covered the British Islands was gradually depressed, while calcareous deposits were sufficiently rapid to keep pace with the sinking. After a long era, vast tracts of ocean beds were elevated into land; and while this upheaval was taking place in England, the deep sea was being enlarged by vast depressions of the ocean bed from Spain to Scandinavia, in which was deposited vast quantities of chalky mud. Afterwards this bed was elevated on a very extensive scale; thus forming land from Britain into Asia Minor, and so producing the central mountain districts of Asia and Europe. This upheaval was accompanied by an almost total extirpation of the animals that lingered in the mesozoic age. Thus we see the dawn and the decline of Saurian reptile life. Then evening was, then morning was-day five.

185

CHAPTER VII.

THE MAMMAL MONSTERS.

OUR survey of the geological history of the earth will become more interesting as, in describing the Tertiary series, we shall approach the human era. We must regard as Tertiary all formations above the chalk up to the close of the boulder drift; and as Quartertiary, all accumulations since that period. The former comprises all those stratified clays, sands, limestones, and gravel which lie between the chalk and drift-beds; while the latter includes all the more recent deposits. These formations are somewhat limited, being contained in the trough-shaped hollows of the chalk beds, which were lakes and gulfs during the close of the secondary series. The organic remains found in the rocks of the Tertiary period, are all more or less allied to existing species. We know that a large per centage of the shells and corals are identical with those of existing orders. The reptiles, fishes, birds, and mammals of all classes, except man, are formed in the rocks. Among the vegetable fossils there is evidence of exogenous timber trees, which increase by external layers of growth, like the oak, the elm, and beech of our day. Thus it is evident

that the God of nature now made another move in an onward and upward direction, throwing aside, as it were, the moulds and patterns of extinct organisms, producing others more adapted to the gradually varying conditions of the world. This life-period stands in remarkable contrast with all that is known of preceding eras. In these we find, so far as geologians know them, that animal life was very imperfect either some great order was largely predominant, or one or more orders were altogether absent. For instance, the Laurentian, Cambrian, and Silurian periods, were characterised by the general absence of vertebratæ, or animals each having a spine with joints. In the Devonian epoch there were neither reptiles, birds, or mammals; while in the secondary ages colossal reptiles and a few marsupial mammals tenanted the earth. But now for the first time we are presented with all the great orders of plants and animals; and were it not for certain forms that have become extinct, we might almost imagine that we were dealing with the zoology and botany of the present day. As a whole, the biological aspect of the Tertiary system is sufficiently distinct from all that went before it. Though many of its species have long since become extinct, there is a much nearer resemblance between them and the animals of our era, than there is between existing nature and any of the ancient periods. Geologians also inform us that the plants of the lower tertiary indicate a much warmer climate than now prevails in the same latitudes; and this higher temperature is supposed to have been caused by the peculiar disposition of the sea and land. They say that broad rivers flowing from tropical latitudes, and inland seas extending longitudinally into sub-tropical