“What?” cried Nat, considerably startled.

“Why, a hand reached out and grasped my hat and——”

Before the professor could conclude his sentence the boys saw a small brown paw project from a ledge above him and whisk his unlucky hat from his head.

“It’s a monkey!” cried Nat.

“A lot of them!” exclaimed Joe.

“T-t-t-there they go,” cried Ding-dong, as a dozen or more apes of the prehensile tailed type rushed off amidst the ruins, chattering and squealing and tearing and clawing at the professor’s unlucky headgear.

“Just to think,” sighed the man of science with resignation, “that I came all this way, and we have made all these discoveries, and yet my ill-fortune with hats pursues me still.”

“I’d give several dozen hats to have seen what we’ve seen,” Nat reminded him.

“That is so! that is so!” Professor Grigg agreed; “but——”

“Look out!” cried Joe, behind him, suddenly.