"Here, that won't do," breathed Jack, as the three lads crouched at the cave mouth. "Throw some rocks at them, Walt."
The boys picked up some small stones, which lay littered in front of the cave, and commenced a fusillade. It had such good results, that a few seconds later, the three horses were plunging off along the bottom of the gully as if Old Nick himself had been after them.
As their hoof-beats grew faint, Jack held up his hand to enjoin silence, although the boys had been discussing their situation in such low tones that their voices could not have traveled ten feet from the cave mouth.
"Hark!" he said.
From farther down the gully came shouts and yells, and then the distinct rattling sound of loose shale, as several horsemen descended the steep bank into the gulch.
"They've picked up the trail," commented Walt grimly.
CHAPTER XVI.
WHAT HAPPENED TO COYOTE PETE.
Let us now retrace our steps to the Haunted Mesa, and ascertain how it fared with Coyote Pete and the professor, after the boys' astonishing disappearance through the balanced trap-door in the base of the hollow altar. As we know, the lads' elders were crouched at the opposite end of the former sacrificial structure, when, before their eyes, the lads were swallowed up.