e_ doing?" screamed Grue, quivering from head to foot, but not
turning around.

"Who?" I cried.

"The man behind me!"

"Professor Kemper? He's setting up the folding cage--"

With a screech that raised my hair, Grue whipped out his murderous knife
and _hurled himself backward_ at Kemper, but the latter shrank aside
behind the partly erected cage, and Grue whirled around, snarling,
hacking, and even biting at the wood frame and steel bars.

And then occurred a thing so horrid that it sickened me to the pit of my
stomach; for the man's sagging straw hat had fallen off, and there, in
the back of his head, through the coarse, black, ratty hair, I saw a
glassy eye glaring at me.

"Kemper!" I shouted. "He's got a third eye! He's one of them! Knock him
flat with your riflestock!" And I seized a shot-gun from the top of
the baggage bundle on the ground beside me, and leaped at Grue, aiming
a terrific blow at him.

[Illustration: "'Kemper!' I shouted.... 'He is one of them! Knock him
flat with your riflestock!'"]

But the glassy eye in the back of his head was watching me between the
clotted strands of hair, and he dodged both Kemper and me, swinging his
heavy knife in circles and glaring at us both out of the front and back
of his head.

Kemper seized him by his arm, but Grue's shirt came off, and I saw his
entire body was as furry as an ape's. And all the while he was snapping
at us and leaping hither and thither to avoid our blows; and from the
corners of his puffed cheeks he whined and whimpered and mewed through
the saliva foam.

"Keep him from the water!" I panted, following him with clubbed shot-gun;
and as I advanced I almost stepped on a soiled heap of foulness--the dead
buzzard which he had caught and worried to death with his teeth.

Suddenly he threw his knife at my head, hurling it backward; dodged,
screeched, and bounded by me toward the shore of the lagoon, where the
pretty waitress was standing, petrified.

For one moment I thought he had her, but she picked up her skirts, ran
for the nearest boat, and seized a harpoon; and in his fierce eagerness
to catch her he leaped clear over the boat and fell with a splash into
the lagoon.

As Kemper and I sprang aboard and looked over into the water, we
could see him going down out of reach of a harpoon; and his body seemed
to be silver-plated, flashing and glittering like a burnished eel, so
completely did the skin of air envelope him, held there by the f