ecognizable strata, had a quick vision of these
caverns being cut out and enlarged, and of their walls melted just as
they were being melted now--melted and hardened again innumerable
times by succeeding generations of red and yellow-skinned men.

Yes, they were men. He admitted this while he walked unresistingly
between two of the giants. Another went before them and lighted the
way with the green ray of a flame-thrower on the melting rock. These
were men--men of a different sort. Evolution, working strange changes
underground, had made them half beasts, diggers in the dark, mole-men!

They were passing through a long tunnel that went steadily down.
Cross passages loomed blackly; ahead of them the leader was throwing
his flame upon the walls of a great vault.

Rawson had ceased to take note of their movements. What use to
remember? He could never escape, never retrace his steps.

He tried to whip up a faint flicker of hope at thought of Smithy.
Smithy had seen him go, had seen the red mole-men, of course. And he
had got away--he must have got away! He would go for help....

But, at that, he groaned inwardly. Smithy would go for help, and then
what? He would be laughed out of any sheriff's office; he would be
locked up as insane if he persisted. Why should he persist--for that
matter, why should he go at all? Smithy would not believe for a single
minute that Rawson was still alive.

* * * * *

His thoughts ended. Webbed hands, wrapped tightly about his arms, were
thrusting him forward into a great room. The green flame had been
snapped off. One last hot circle on the high wall showed only a dull
red. But before it faded, Dean saw dimly the outlines of a tremendous
cavern. He saw also that these walls were unglazed, raw; they had
never been melted.

Below the rough and shattered sides heaps of fragments were piled
about the room.

Fleetingly he saw the shadowed details; then darkness swallowed even
that little he had seen. Clanging metal told of a closing door; a line
of red outlined it for an instant to show where it was welded fast. He
was a prisoner in a cell whose walls were the living rock.

For a long time he stood motionless, while the heavy darkness pressed
heavily in upon his swimming senses; he sank slowly to the floor at
last. He was numbed, and his mind was as blank as the black
nothingness that spread before his staring eyes. In a condition almost
of coma, he had no