"Not for fifteen years," laughed Rhoda.

Just then, to their surprise, not to say their fright, there came
to their ears a most startling sound out of the darkness of the
cave!

It was a more uncanny noise than any of the young people had ever
in their lives heard before. Rising higher, and higher, shriller
and yet more shrill, the sound seemed to shudder through the cavern
as though caused by some supernatural source. There was nothing
human in a single note of it!

"Oh!" whispered the shaking Grace, "is that a bear?"

"Never in this world!" exclaimed Nan.

"I don't know what it is," asserted Bess. "But if it is a bear, or
not, I hope it doesn't do it again."

"Rhoda, what do you think?" demanded Nan, in an awed undertone.

"Hush!" returned the Western girl. "Listen."

"I don't want to listen--not to that thing," declared Bess, with
conviction. "It's worse than a banshee. Worse than the black ghost
at the Lakeview Hall boathouse."

Once more the noise reached them; and if at first it had startled
the four girls, it now did more. For the ponies whose bridles they
held, showed disturbance. Grace's mount lifted his head and