Armed with his rifle, and with provisions sufficient for his journey strapped upon the back of his sturdy little pony, Reuben departed from the camp. The way he was to follow lay for a time among the hills. In the heart of the excited boy there was a feeling of elation that he had been selected for this journey. He was eager to show Kit Carson and his comrades that they could depend upon his coolness and that he would be able to make his way in safety to the old mission and there deliver his message. He was mindful of the heat of the plains and of the length of the journey and consequently he did not urge his pony. At last he found himself among the narrow defiles of the bleak and towering Sierras. It was not difficult for him to retrace the way by which he had come from the old mission the last time he had visited the station. It was now early in the morning, and he was hopeful that before sunset he would once more be among the friendly Indians and the whites who dwelt at San Gabriel. The morning passed without any adventures, and the afternoon sun was waning when at last Reuben entered a defile that was, as he recalled it, several miles long. On his left were stunted growths of trees and the sides of the mountains sloped gently back with the valley. On the opposite side, however, the cliffs were steep and the mighty crags in places hung directly over his pathway. He was following the bed of a stream, which was nearly dry, as the snows had largely disappeared from the slopes of the mountains. The sense of his absolute loneliness was resting more heavily upon him now that he was tired from the long ride. Suddenly the pony stopped and trembled violently in every muscle. An instant later the frightened animal did its utmost to leap forward, and it was only by using all his strength that Reuben was able to restrain him. Then it was that he glanced behind him to discover the cause of the terror of his horse. His own alarm was hardly less when not more than twenty yards behind him he saw the crouching figure of a mountain lion. The savage beast evidently was following him, occasionally seeking the shelter of some huge rock, or climbing among the bushes. It was unusual, however, for such treacherous animals to come into the open, as the one behind him now was doing, and for a moment Reuben was at a loss to account for the tenacity with which the powerful beast had been clinging to his trail. Instantly Reuben raised his rifle to his shoulder and fired. At that very moment, however, his pony, maddened by terror, suddenly leaped forward, and the aim of the young hunter was destroyed. It was plain an instant later that the savage mountain lion was unharmed. CHAPTER XVI—A MOUNTAIN LION