"We're killed!" howled Chunky.

"Help, help!" yelled Walter Perkins.

"What---what is it?" roared the Professor.

"We're struck!" shouted Tad.

"Lie still. Hug the wall!" bellowed the stentorian voice of Jim Nance,
who himself had crept closer to the Canyon wall and lay hugging it
tightly.

The deafening, terrifying reports continued. One corner of the ledge
over their heads split off, sending a volley of stones showering over
them, leaving the faces of some of the party flecked with blood where
the jagged particles had cut into their flesh.

It was a terrible moment for the Pony Rider Boys.




CHAPTER X

ESCAPE IS WHOLLY CUT OFF


Not one could collect his thoughts sufficiently to reason out what had
taken place. The guide, however, had known from the first. He feared