"Sure," laughed Billie, thoroughly enjoying the perplexity of his companions. "My friend Ab. Come here, old man, and be introduced," and Billie waved his whip, which he still carried. With a little cry the ape sprang to his side, an act which only added to the amazement of the others. "Allow me," said Billie with mock gravity, "to introduce my friend Mr. Ab from No-man's-land. Ab, these are the rest of the Broncho Rider Boys. How would you like to join the company?" Ab scratched his ear and looked wise. "Oh, come," interrupted Donald. "Tell us what's up and what we must do to capture the rest of this band of cutthroats." Thinking that he had carried the joke far enough, and realizing also that he might be wasting valuable time, Billie related his adventure, describing the place he had discovered. "It is the Rosario viejo," said Pedro, as soon as Billie had finished his story. "What's that?" asked Billie. "An abandoned mine. It is called the old Rosario to distinguish it from the new Rosario, which is now one of the most valuable mines in this region. The station at Pitahaya was built especially to serve it." "I see," said Billie. "Where is the new mine?" "Down there," and Pedro pointed to a trail leading in the opposite direction. "It is just about as far from the station on that side of the railroad as the old Rosario is on this." "Don't you think we had better summon some assistance from the mine workers?" asked Adrian. "They may be in cahoots with the bandits," laughed Donald. "I have lost my confidence in about every one in this bandit-ridden land." "I don't blame you," said Pedro, "and I hope the day will soon come when all this trouble will be over." "Then you agree with me that we should tackle the bandits alone, do you?" asked Donald. "It is the only safe way." "All right, then," exclaimed Billie. "Let's be off. If we use a little strategy, I'm sure we shall succeed." He turned to mount the horse, which a minute before had been standing a few feet away, but it was gone. "Where's my horse?" he cried. The others turned in surprise. "It certainly was here a minute ago," declared Adrian. "Then it can't be very far away," insisted Donald. "It's so far I can't see it," replied Billie. "There it goes!" shouted Pedro, who had jumped his mount across the track as soon as he heard Billie's cry. The others looked in the direction indicated, and sure enough, there went the horse about a quarter of a mile away on a dead run and on its back was Billie's late acquaintance, Ab. "By George," exclaimed Billie angrily as he snatched a rifle from Donald's holster, "I've had enough of that ape. I'll put a stop to his foolishness," and he leveled the rifle. But ere he could press the trigger, there was a report from another quarter and the horse and its rider hit the dust. CHAPTER V. WHEN THE OLD WAS NEW. A cry of astonishment went up from the quartette and then they stood silent to see what would be the next move.