“Now I see their scheme,” Stanley exclaimed. “They have taken their stand for the night out in the open, where they have a chance for their lives. I doubt if even the sabre-tooths would dare charge that front of horns and hoofs. In the forest they could pick them off singly without much trouble, but——”
A small stone struck Ted’s shoulder, dropped to the ledge, bounded off, and rattled down to the ground.
“Where did that come from?” he asked with a start.
They looked up along the face of the stone wall, but saw nothing.
“Just a loose fragment,” Stanley explained with a nervous laugh. “Probably small pieces are dropping all of the time, or an owl may have started it in alighting.”
Again they strained their eyes toward the moonlit floor of the crater.
“I don’t remember seeing that stone before—the one right below and a little to the left.”
“Nor I. But it must have been there, just the same, for stones can’t walk.”
“How smooth and round it looks. The moonlight and shadows make it appear more conspicuous than before; that is why we notice it now.”
“Yes; I guess you are right.”