g into the current of the
Madeira.

Old Gurlone, of the livid face, was in charge of one boat, and the
gigantic Portuguese, with his colorless eyes and burned complexion,
sat beside him.

That night, the two tropical tramps stole a small boat with a
one-cylinder motor, and started up the river.

It was a hard journey, but they were used to river and jungle work,
and the object they had in view was enough to make them discount
trouble. They speculated upon what manner of treasure it was they
would find in the cavern of the Matto Grosso mine. It might be
precious stones, it might be gold. Certainly it was something very
valuable.

They carried little supplies, but they were heavily armed. For food,
they might hunt and also depend on the caches left by their friend,
Juan the peon.

Three hundred miles from Manaos, they came to the landing where old
Gurlone had unloaded his boats. The two tramps drew their own craft up
on shore a quarter of a mile away, keeping out of sight, and hid the
boat in dense brush. Then they crept up the river bank, keeping out of
sight of the boatmen, who were preparing for the return voyage, and
cut into the jungle so as to strike the trail of the caravan ahead.

For several hours they followed the path easily. They found palm trees
blazed with new marks, and these they were sure their friend Juan had
left for them. But the trail was easy to keep without these. The
supplies had been loaded on burros, which had been awaiting the
boats.

That night, they camped beside a small stream. They were but
twenty-four hours behind Professor Gurlone and his party, and the food
Juan had cached for them was in good condition.

* * * * *

They were up at daybreak, and pressed on, armed to the teeth and ready
for a fight.

"What's that?" said Durkin, stopping so suddenly that Maget ran into
him.

They had been walking at a swift pace along the jungle path, the giant
trees forming a canopy overhead. Monkeys screamed at them, birds
flitted a hundred feet above them in the roof of the forest.

The sun beat on the jungle top, but few rays lightened the gloom
beneath.

From up ahead sounded a frightful scream, followed by a long drawn out
wailing. Maget glanced at Durkin, and the latter shrugged, and pressed
on. But he gripped his rifle tightly, for the cries were eery.

From time to time the two stopped to catch better the direction of the
wails. At last, they loca