ght the lower caverns.

"Very clever!" said Ray. "They make the stuff up there at the cone and
run it in here to see by."

"This warm air feels mighty good," I remarked, pulling off another
garment.

Ray sniffed the air. "A curious odor. Smells like something growing.
Where anything is growing there ought to be something to eat. Let's
see what we can find."

Only black obsidian covered the floor about us. Cautiously we skirted
the overflowing pool of white fire, and followed down the stream of it
that flowed toward the inner cavern. We had gone but a few hundred
yards when suddenly Ray stopped me with a hand on my arm.

"Lie flat!" he hissed. "Quick!"

He dived behind a huge mass of fire-born granite. I flung myself down
beside him.

"Something is coming up the trail by the shining river. And it isn't a
man! It's between us and the light; we should be able to see it."

* * * * *

Soon I heard a curious scraping sound, and a little tinkle of metal. I
caught a whiff of a powerful odor--a strange, fishy odor--so strong
that it almost knocked me down.

The thing that made the scraping and the tinkle and the smell came
into view. The sight of it sickened me with horror.

It was far larger than a man; its body was heavy as a horse's, but
nearer the ground. In form it suggested a huge crab, though it was not
very much like any crustacean I had ever seen. It was mostly red in
color, and covered with a huge scarlet shell. It had five pairs of
limbs. The two forward pairs had pinchers, seemingly used as hands; it
scraped along on the other three pairs. Yard-long antennae, slender
and luminously green, wavered above a grotesque head. The many facets
of compound eyes stood on the end of foot-long stalks.

The amazing crab-thing wore a metal harness. Bands of silvery aluminum
were fastened about its shell, with little cases of white metal
dangling to them. In one of its uplifted claws it carried what seemed
to be an aluminum bar, two feet long and an inch thick.

It scraped lumberingly past, between us and the racing stream of white
fire. It passed less than a dozen feet from us. The curious fishy
smell of it was overpowering, disgusting.

Sweat of horror chilled my limbs. The monster emanated power,
sinister, malevolent power, power intelligent, alien and hostile to
man.

I trembled with the fear that it would see us, but it scrambled
grotesquely on. When it was twenty yards past,