Adrian looked at the man and winked one eye very slowly.

"Señor, it is true," spoke up another. "I was a guard at the time."

Adrian could scarcely believe the statement, but he afterward learned that the men spoke the truth.

"Well, then," he said, "we had better look to our arms, for we may need them. There is no knowing how this affair has turned out."

The advice was well taken, for as they drew near the scene of the wreck, they saw that they were badly needed. More than a dozen horsemen were in sight at some distance from the wreck and with their long-range rifles were doing their best to pick off any one who showed his head.

"Our party must be out of ammunition," suggested Adrian, "or they would give a better account of themselves."

"Our carbines would not carry that far," explained one of the guards.

"Our Marlins will," replied Adrian, and as he spoke there were two simultaneous flashes from two of the car windows and two of the bandits fell, one shot from his horse and the other with his horse shot under him.

For a moment the other horsemen hesitated as to the course they should pursue and then, putting spurs to their horses, they dashed toward the train, just as the express car, having reached the end of the track, bumped onto the ties and came to a stop.

"Now!" cried Adrian as the riders drew near, firing as they came, and four shots rang out.

The volley from so unexpected a quarter took the horsemen completely by surprise, and they pulled up with a jerk. The action proved their undoing, for as they stood thus for a moment, they gave those in the train the opportunity they desired and the volley that followed turned four more riderless horses upon the plain.

It was more than flesh and blood could stand, and the seven or eight remaining horsemen turned and fled, followed by at least three whistling bullets from as many Marlins.

The fight was over and the bullion had been saved, but what of Broncho Billie, who had been left at the top of the hill four miles away?

That was the first question asked by Donald when he greeted Adrian two minutes later.

"Oh, he's all right," was the laughing reply. "He's just taking a little walk for his health."

But when Billie failed to put in an appearance an hour later, the boys mounted their horses and started up the track to meet him, leading Billie's mount between them.

CHAPTER III.

BILLIE LOSES HIS NERVE.

Broncho Billie was not a rapid walker. In fact, if there was any one thing in which Billie was not a success, it was walking. He could ride a horse all day, but when it came to depending upon his own legs as a means of locomotion, he was a dead failure.

Therefore he walked slowly along, counting the ties as he went.

"They certainly do lay 'em thick," he mused after some minutes. "Three hundred and one, three hundred and two, three hundred and three, three hundred and four, three hun——"

He stopped short and looked behind him.

"I sure thought I heard some one," he muttered. "It must have been a bird."

He turned and started forward.

"Let's see, where was I? Oh, yes, three hundred and five, three hundred and six, three hundred and——"

Again he stopped, but did not turn around. Instead he stooped down as though to pick up a stone, which enabled him to look backward between his knees.

He caught a movement in the grass at the edge of the right of way.

"I thought so," he muttered. "Now to find out who it is, and what he wants."

He picked up a small stone and threw it at a tall cactus which grew near the track some distance ahead.

"Good shot," he said aloud as the stone hit the stalk. "I wonder if I could do it again."

He stooped down and picked up another stone, taking a good look backward from his stooping position. There was not a movement to indicate the presence of a living thing.

"This is getting on my nerves," the boy mused as he picked up several small stones and again walked forward. "I don't mind being followed by a white man, but I'm a whole lot leary of these greasers. They're bad enough when they're friendly."

Then aloud, as he threw a couple of stones: "I'll never get anywhere if I don't make better time than this. I'll just sprint a few."

Suiting the action to the word, he started on a run.

Almost immediately he was aware of a soft pat-pat in his rear. He had heard a similar sound in the wilds of Wyoming and he recognized it at once.

It was the footfall of a four-legged animal.

"So!" he ejaculated. "I wonder what it is. If there were wolves down here I would say it was a wolf, but I don't believe there are." Then a minute later, "Well, whatever it is, I'm going to find out."

He whipped out his automatic and turned suddenly.

As before, not a single living thing was in sight, only in the grass a movement as before.

Without a moment's aim, he fired a single shot at the spot. It was an act born of fear and Billie knew it, but for the life of him he could not have done otherwise, so nervous had he become.

The report was followed by a cry of pain and an instant later there came running directly toward him out of the tall grass a figure so weird that Billie stood as one paralysed.

The figure was that of a man not more than two feet high, with long arms and a head of diminutive size. While it stood upright at times, at others it came forward on all fours. To Billie it seemed a cross between a man and a monkey.

Gathering his wits in an instant, Billie would have fired again—in fact, raised his revolver to do so, when the strange creature fell to its knees and raised its hands in supplication.

"By George!" exclaimed the lad as he stood with lowered weapon. "What kind of a thing is this? I wonder if it can talk?"

Then as he took a step toward it: "I'm not going to hurt you. Come here."

The creature arose to its feet and came slowly toward him. As it did so Billie noticed that blood was running from a wound in its scalp.

"Poor thing," he said. "That must have been where the bullet hit him. It was a close shave."

"Can you talk?" he finally asked.

The strange creature turned its head to one side and eyed him closely, but no sound came from its lips.

"It must be an ape of some sort," mused the boy; "but how did it become so tame?"

He slowly returned his automatic to its holster, thinking in the meantime how he could dress the creature's wound; but no sooner had his hand left his weapon than the ape sprang at him with the utmost fury. It landed on his shoulder, wound its legs about his neck, and with its long arms made a wild grab for the revolver.

Then began a strange and terrible struggle for the possession of the weapon. Even as he fought the beast, Billie realized that in some manner the ape had learned to fear firearms, but whether it had ever learned to use them he could not venture a guess. He felt certain if he could draw the weapon and point it at the ape, it would at once cringe in fear. What might happen if the ape should get possession of it, he could only imagine.

For a youth of eighteen, there were few whom Billie met that were his match physically, but this diminutive man-animal held him as in a vise. Billie exerted every ounce of his strength to free himself from the terrible hold, while the ape fought even more fiercely to retain its grip and to gain possession of the weapon.

It was a weird and fearful struggle waged there in the stillness of the tropical woodland—a