error slid from his pony, sending up a little
cloud of dust as he collapsed on the plain.

"Wha---what---what-----" gasped the professor.

Bang!

Professor Zepplin's sombrero was snipped from his head. Stacy lay
groaning on the ground.

"Ride for the rocks!" shouted Tad as shot after shot began popping from
somewhere in the mountains, the bullets screaming over their heads
close to their ears or snipping up flecks of dust in the plain.

Tad drove his pony straight at Stacy Brown. He scooped the fat boy up
by the collar and rode madly for the protection of the rocks, Chunky's
heels dragging on the ground. The others rode madly after them, while
the shots were still being fired at them. It was an exciting moment.
No one knew what the shooting meant, nor did they know whether Stacy
really had been hit or not. There was no time to stop to reason the
matter out. It was a case of getting to cover as fast as horse-flesh
would carry them.

CHAPTER II

A MYSTERIOUS ATTACK

"Pull in close!" cried Tad.

"Where is it coming from?" shouted Ned.

"I don't know. I haven't had time to look. Look out there!"

Professor Zepplin, somewhat slower than the others, had halted a little
distance out from the foothills. A bullet threw up a little cloud of
dust just to one side of where he was sitting on his pony, followed by
a report somewhere up in the mountains.

"Stop that! Stop it, I tell you!" bellowed the professor, waving his
sombrero. Almost ere the words were out of his mouth, the sombrero
was shot from his hand and went spinning out to the rear. Professor
Zepplin did not wait for further parley. He turned his horse, dashing
for the protection of the foothills.

In the meantime, Tad Butler had leaped from his pony, placing Stacy on
the ground. It was observed that there was blood on the fat boy's left
cheek, but his eyes, wide and frightened, were staring up at the boys
now gathering about him.

"Are you hurt?" demanded Tad breathlessly.

"I'm killed."

"Nonsense! It's only a flesh wound---"

"Is---is he shot?" stammered Walter Perkins.

"Of course I'm shot. Don't you see I am?" demanded Chunky with
considerable spirit for a man who had been the mark of a bullet and who
according to his own word was dead.

Tad half dragged the fat boy down to the creek where the blood was
quickly washed from his cheek. It was then seen that a bullet had
grazed Stacy's cheek, leaving a raw streak across i