Suddenly one of the forefeet of his horse sank into a hole which the prairie-dogs had made. Glancing about him, Reuben saw that he was in the midst of a village of the little animals. With an effort he maintained his seat in the saddle, for he was an expert horseman, and an ordinary fall had little peril for him. This time, however, his horse was unable to regain its foothold. It stumbled and staggered several steps, and then with a groan sank to the ground. As it fell, Reuben slipped from its back and leaped lightly to the ground. Advancing to the head of his horse, he seized the bridle and attempted to lift the animal to its feet. It was unable to rise, and a brief examination convinced the young trapper that the fall had broken its leg. The thunder of the flying herd now sounded farther away. In the dim light Reuben saw that the buffaloes were still running swiftly and were headed for a valley or defile among the hills not far distant. Once there, doubtless they would be secure from attack. His own predicament, however, was too appalling to enable Reuben long to think of the fleeing herd. He was miles distant from his companion, his horse had fallen with a broken leg, and night was upon him, while his perils doubtless would be greatly increased before morning came. For a moment the heart of the young hunter was heavy. A groan of his faithful pony recalled him to the necessity of action. There was no hope of restoring the suffering brute, and, advancing to its head, without hesitating a moment, Reuben fired at the heart of the panting, suffering animal. With scarcely a quiver the horse became still. His own problem, however, was still unsolved, as Reuben now was fully aware. The cloud of dust in part had disappeared in the dim light. He looked all about him, but not a trace of Jean or the camp was he able to discover. He was alone on the trackless plains and by no means certain of the direction in which he had come or of the way in which he should go. CHAPTER III—THREE CHEYENNES Reuben was aware that he was not far from the base of one of the highest mountains. As once more he looked up and peered intently in every direction, he was aware also that no one was within sight. The poor beast on which he had ridden was dead and there was no means by which the young trapper might return to the camp where he had left his friend. In the distance the herd of buffaloes still could be seen, a tiny mass moving across the plains in the dim light. Even while he was gazing at them they disappeared and were lost to sight among the foothills. Reuben was aware that he had shot one cow, but where the animal had fallen or how far it was from the place where he now was standing he had no means of knowing. He looked behind him, but was unable to discover even his own trail in the sand. All traces had been destroyed by the hoof-prints of the mighty herd of fleeing animals.