t world--" But Chet
held to another thought.

"Who--who built it?" he asked. "It's tremendous! There is nothing like
it on Earth!"

* * * * *

Only Kreiss seemed oblivious to the weird beauty of the spectacle. To
Professor Kreiss dolomite and black flint rock were dolomite and black
flint; interesting specimens--a peculiar arrangement--but nature must be
permitted her little vagaries.

"Who built it?" He repeated Chet's question and gave a short laugh
before answering in words. "The rains, Herr Bullard, and the winds of
ages past. Yes, yes! A most remarkable example of erosion--most
remarkable! I must return this way some time and give it my serious
attention."

Harkness had not spoken; he was shaking his head doubtfully at Kreiss'
words. "I am inclined to agree with Chet," he said slowly. "But who
could have built a gigantic work like this? Have there been former
civilisations here?"

He straightened up and shook himself free from the effects of the wild,
barbaric scene.

"And you needn't come back," he told Kreiss; "you can have a look now,
to-night, by moonlight. We can't go on. I think we'll be safest on that
big altar rock; nothing will get near us without our knowing."

Chet felt Diane Delacouer's hand on his arm; her other hand was gripping
at Harkness. The shiver that passed through her was plainly perceptible.
"I'm afraid," she confessed in a half-whisper; "there's something about
it: I do not like it. There is evil there--danger. We should not enter."

Walt Harkness gently patted the hand that trembled on his arm. "I don't
wonder that you are all shot to pieces," he assured her. "After last
night, you've a right to be. But I really believe this is the safest
spot we can find."

* * * * *

He stepped forward beyond the great stones that were like a gateway from
one wildly impossible world to another. A rock slide, it seemed, had
smoothed off the great steps from where they stood, for there was a
descending slope that gave easy footing. He took one step, and then
another, to show the girl how foolish were her fears; then he started
back. In the fading light something had flashed from the jungle they had
left. Across the rocky expanse it came, to bury itself in the loose soil
and rubble, not two paces in advance of the startled man. An arrow!--and
it stood quivering in silent warning on the path ahead.

Chet quietly unslung his bow wher