All day he watched for the return of Oo. The great apes and the lesser apes passed below and above and around him. Sometimes they threw him a word in passing. Below, the woolly rhinoceros browsed and lay down to sleep. A pack of hyenas slunk down from the plateau above the cliffs. They circled the sleeping perissodactyl. The great beast opened its little eyes. Lumberingly it came to its feet, wheeling about until it faced up wind, then, like a mountain run amuck, it charged straight for the line of now growling hyenas. The cowardly brutes leaped aside, and the whole pack closed upon the rear of the rhinoceros. The big beast turned, quick as a cat. Down went his armed snout and one of his tormentors was hurled far aloft, torn by the mighty horn that had pierced him through. Again the rhinoceros wheeled and ran, and again the pack closed in upon him. The jungle swallowed them, but for a long time Nu could hear the savage growls of the pursuing beasts, and the yells of pain as from time to time the rhinoceros turned upon his tormentors.

Then came a cave-bear, lumbering down the face of the cliff. At the mouth of the cave of Oo he halted sniffing about warily, and uttering deep throated growls of rage and hate. Nu listened for the answering challenge of the ancient enemy of Ur, but no sound came. Nu shrugged his shoulders. It was evident that Oo was far away, otherwise he would never have let Ur's challenge go unanswered.

Now the bear had continued his way to the foot of the cliff. He was advancing toward the tree in which Nu sat. At the edge of the jungle the beast halted and commenced to nose in the soft earth for roots. Nu watched him. If not the head of Oo, why not the head of Ur? Oo would not return that day, of that Nu was positive, for it was already late in the afternoon and if the great tiger had been near he would have heard and answered the challenge of the cave-bear.

Nu dropped lightly to the ground upon the opposite side of the tree from Ur. In his right hand he grasped his long, heavy spear. In his left was his stone ax. He approached the huge beast from the rear, coming within a few paces of it before the animal was aware of his presence, for none of the jungle folk moved more noiselessly than primeval man.

But at last Ur looked up, and at the same instant Nu's mighty muscles launched the stone-tipped spear. Straight as a bullet it sped toward the breast of the hairy monster, burying itself deep in his body as he lunged forward to seize the rash creature that dared attack him.

Nu held his ground, standing with feet apart and swinging his heavy stone ax to and fro in both hands. The cave-bear rose upon his hind feet as he neared the man, towering high above his enemy's head. With gaping jaws and outstretched paws the terrible beast advanced, now and then tearing at the stout haft of the spear protruding from its breast, and giving tongue to roars of rage and pain that shook the earth.

As the mighty forearms reached for him, Nu dodged beneath them, swinging his ax to the side of the bear's head as he passed. With a howl the beast wheeled and charged in the new direction, but again Nu followed his previous tactics, and again a crushing blow fell upon the side of the cave-bear's jaw.

Blood spurted from the creature's mouth and nostrils, for not only had the stone ax brought blood, but the stone spear had penetrated the savage lungs. And now Ur did what Nu had been waiting for him to do. He dropped upon all fours and raced madly toward his tormentor. The changed position brought the top of the skull within reach of the man's weapon, and this time, as he sidestepped the charge, he brought the ax down full upon the bear's forehead, between his eyes.

Stunned, the beast staggered and stumbled, his nose buried in the trampled mud and grass of the battlefield. Only for an instant would he be thus, and in that instant must Nu leap in and finish him. Nor did he hesitate. Dropping his ax he sprang upon Ur with his stone knife, and again and again sent the blade into the wild heart. Before the cave-bear regained full consciousness he rolled over upon his side, dead.

For half an hour Nu was busy removing the head, and then he set himself to the task of skinning the beast. His methods were crude, but he worked much faster with his primitive implements than modern man with keen knives. Before another hour had passed he had the skin off and rolled into a bundle, and had cut a great steak from Ur's loin. Now he gathered some dry leaves and tinder and with a sharpened bit of hard wood produced fire by twirling the point vigorously in a tiny hollow scooped from another piece of hard wood. When the blaze had been nursed to a fire of respectable dimensions, Nu impaled the steak upon a small branch and squatting before the blaze grilled his supper. It was half burned and half raw and partially smoked, but that he enjoyed it was evidenced by the fact that he devoured it all.