and knock him senseless,
might have sense enough to fire a revolver.

"If I only knew something about his history," soliloquized
Billie, "I might be able to guess how much he knew. But he is a
perfect stranger to me. I don't even know his name."

After several minutes and nothing had happened, Billie decided to
make some effort to get away.

"I might as well be shot as to be prisoner to an ape," he
thought, and so he arose to a sitting posture and surveyed the
scene.

There sat the ape as before, with the automatic pointed at
Billie, but with a puzzled look upon its face. When the lad
finally arose, the ape appeared still more puzzled and at length,
turning the weapon away from Billie, looked into the muzzle.

"That settles it," exclaimed Billie. "He doesn't know how to fire
it. I'll go and take it away from him."

He started toward the animal, which at once pointed the revolver
in Billie's direction. There came a sharp report and a bullet
whizzed by the boy's head.

"Worse and more of it," exclaimed Billie. "He doesn't know how to
use the thing, but he's liable to shoot me as long as I stay in
range. I'll just make myself scarce."

Stooping down, he picked up a good-sized stone and hurled it at
the ape and then, without waiting to see the result of his throw,
jumped into the jungle which lined both sides of the track,
determined to make a detour and if possible lose his unpleasant
companion.

He had not run far before he realized that the ape was following,
but this he did not mind. There were plenty of trees between
them, and he felt sure he would soon be able to reach some sort
of a habitation, when he suddenly found himself on the edge of a
deep basin into which he plunged before he was able to gain his
equilibrium.

CHAPTER IV.

THE ROSARIO VIEJO.

To be suddenly pitched head-foremost down a rocky declivity into
a mass of prickly pear bushes and other tropical brambles is by
no means pleasant; and as a result Billie was not in the best of
humor when he picked himself up and looked to the top of the
60-foot embankment down which he had slid.

"It's a wonder they wouldn't hang out a red light when they dig a
hole like this," he declared angrily, "and not let a fellow most
break his neck, to say nothing of scratching his eyes out! This
is worse than a subway cave-in."

He pulled himself together and surveyed his surroundings.

The basin looked very much like an old quarry--so old that t