The ruse almost landed him into the jaws of the nose-horned lizard, the carnivorous Ceratosaurus, twenty feet in height, and he doubled back, actually under its fore-limbs, as its large head and formidable flesh-tearing teeth threatened the unicorn, which reared and refused the combat. The moment’s respite as the monsters faced each other, gave Perry a chance to breathe. “Where now?” he gasped, glancing round wildly for some place to hide. But, in that flat expanse, with the araucarias and tree-ferns only a green blur in the distance, there was no cover. The unicorn saw him and charged again. Some strange instinct told him what to do. Again doubling around the huge dinosaur, the boy cast himself despairingly on the back of a creature browsing a few feet away. “Up!” he yelled. As though impelled by the terror in the boy’s voice, or by the still greater terror of sound in that silent world, the light-limbed Anchisaurus rose to its kangaroo-like attitude and began clumsily to run. Some twenty feet of start was gained before the unicorn caught sight of him and then the chase began. The Anchisaurus, more terrified even than the boy by this strange creature clinging to its neck, and driven on by the gleaming horn behind, leaped into full stride, covering ten feet at every step. If the gallop of the unicorn had been hard to bear, this swaying run was worse, for, as the Anchisaurus swung first one foot then the other, the neck and tail rolled to the opposite side to maintain the creature’s balance. No cockle shell on a stormy sea ever tossed as did Perry on the Anchisaurus’ neck. But it was his only chance of safety from that gleaming horn behind, and tightly with arms and legs he gripped the creature’s neck above the shoulder. The sun was nearly down, but a slight, a very slight rise in the ground gave firmer footing, both to unicorn and Anchisaurus, so the speed of both increased. Little by little the lumbering saurians began to grow fewer and at last were seen no more. In their place came spiny lizards, at first few in number, then more and more, huge and monstrous, until in the dim twilight and the silver glow of the rising moon, their threatening shapes seemed like a world of jagged rocks heaving as the billows of a tempest-whipped lake. Then, as though determined to give battle to its strange pursuer, the Anchisaurus stopped, and Perry, fearing that his strange mount would find some swift accounting for his temerity, slipped off, again to face the unicorn. There was no need. [Illustration: _Courtesy of American Museum of Natural History._ STEGOSAURUS, THE SUPER-DREADNOUGHT OF OLD. Huge armored monster of the reptile world, thirty-five feet long, as tall as a modern elephant to the top of the spines, protected by sharp horny plates against the attacks of flesh-eating giants.]