That was enough. No matter how terrible the Dyal might be, it was meat and Tar-gash was hungry, and so the two beasts of prey crept warily forward, stalking their quarry. A vagrant breeze, wafting gently down the canyon, brought to the nostrils of the ape-man a strange, new scent. It was a bird scent, slightly suggestive of the scent of an ostrich, and from its volume Tarzan guessed that it might come from a very large bird, a suggestion that was borne out by the loud screeching of the creature, intermingled with which was a scratching and a scraping sound. Tar-gash, who was in the lead and who was taking advantage of all the natural shelter afforded by the fragments of rock with which the canyon bed was strewn, came to a halt upon the lower side of a great boulder, behind which he quickly withdrew, and as Tarzan joined him he signalled the ape-man to look around the corner of the boulder. Following the suggestion of his companion, Tarzan saw the author of the commotion that had attracted their attention. Being a savage jungle beast, he exhibited no outward sign of the astonishment he felt as he gazed upon the mighty creature that was clawing frantically at a crevice in the cliffside. To Tarzan it was a nameless creature of another world. To Tar-gash it was simply a Dyal. Neither knew that he was looking upon a Phororhacos of the Miocene. They saw a huge creature whose crested head, larger than that of a horse, towered eight feet above the ground. Its powerful, curved beak gaped wide as it screeched in anger. It beat its short, useless wing in a frenzy of rage as it struck with its mighty three-toed talons at something just within the fissure before it. And then it was that Tarzan saw that the thing at which it struck was a spear, held by human hands--a pitifully inadequate weapon with which to attempt to ward off the attack of the mighty Dyal. As Tarzan surveyed the creature he wondered how Tar-gash, armed only with his puny club, might hope to pit himself in successful combat against it. He saw the Sagoth creep stealthily out from behind their rocky shelter and move slowly to another closer to the Dyal and behind it, and so absorbed was the bird in its attack upon the man within the fissure that it did not notice the approach of the enemy in its rear. The moment that Tar-gash was safely concealed behind the new shelter, Tarzan followed him and now they were within fifty feet of the great bird. The Sagoth, grasping his club firmly by the small end, arose and ran swiftly from his concealment, straight toward the giant Dyal, and Tarzan followed, fitting an arrow to his bow. Tar-gash had covered but half the distance when the sound of his approach attracted the attention of the bird. Wheeling about, it discovered the two rash creatures who dared to interfere with its attack upon its quarry, and with a loud screech and wide distended beak it charged them.