s groan," said Tom "Ghosts always groan, you
know."

"And let us order them back," added Sam.

"But be sure to do it in very ghostlike tones," warned Dick. "If our
voices sound a bit natural they'll get suspicious at once. If they
come for us, or shoot at us, drop behind the rocks and run into the
woods."

It must be confessed that the boys were doubtful of the success of
their ruse. Yet they felt they must do something to hold the treasure
seeking party in check, at least until morning. With the coming of
daylight they could signal to the _Rainbow_ and with the aid of those on
the steam yacht probably rout the enemy.

The Rover boys advanced along the trail until they reached a spot they
deemed favorable for their purpose. Then Dick gave his brothers a few
more directions.

Presently they saw the rays of the gas lamp and the lantern in the
distance. At once Tom set up a deep groaning and Sam and Dick joined
in.

"What's that?" asked Shelley, who was the first to hear the sounds.

"Sounds like somebody in distress," answered Sid Merrick.

"Thought you said there was nobody on this island?" came from Cuffer.

"Didn't think there was. Maybe it's some native who--"

"Look! look!" screamed Tad Sobber and pointed ahead with his hand.
"What's that?"

"What's what?" asked the men in concert.

"There--that thing bobbing up and down over the rocks?" And Tad
Sobber trembled as he spoke. This lonely walk through the darkness of
the forest had somewhat unnerved him.

"That's strange," muttered Merrick. "It's groaning!"

"It's a ghost!" screamed Tad, and shrank back, as did Cuffer and
Shelley.

"A ghost?" repeated Sid Merrick. "Nonsense! There are no such things
as ghosts."

"It cer-certainly looks like a-a ghost!" faltered Cuffer.

"It is a ghost!" said Tad, his teeth beginning to chatter. "I-I ca-can
hear it gro-groan! Come on ba-ba-back!" And he began to retreat.

"Back with you!" came in solemn tones. "Back with you!"

"No white man must come here," said a second voice. "This is sacred
ground!"

"He who sets foot here dies!" came from a third voice. "This is the
burial place of the great Hupa hupa! Back, if you value your life!"
And then followed a jabbering nobody could understand, and white arms
were waved wildly in the air.

This warning was too much for Tad Sobber, and without further ado he
took to his heels and retreated down the trail whence he had come.
Cuffer followed him, and Shelley also r