able to stand right up to us and not be handicapped by lack of water to
breathe ... I wonder.... Is that part of their plan? Is there any way
they could manage ...?"

"But, Professor," I argued, "it's all over, isn't it? The tunnel is
emptied, and all the Quabos are--"

"The tunnel isn't emptied. It's only _half_ emptied! I'll show you."

He called Stanley; and the three of us went to the break.

"See," the Professor pointed out to us as we approached the jagged hole,
"the Quabos only drilled through the top half of their tunnel ending.
That means that the tunnel still has about four feet of water in
it--enough to accommodate a great many of the monsters. There may be
four or five hundred of them left in there; possibly more. We can expect
renewed hostilities at any time!"

"But won't it be just a repetition of the first battle?" remonstrated
Stanley. "In the end they'll be killed or will drown for lack of water
as these first ones did."

* * * * *

The Professor shook his head.

"They're too clever to do that twice. The very fact that they kept half
their number in reserve shows that they have some new trick to try.
Otherwise they'd all have come at once in one supreme effort."

He paced back and forth.

"They're ingenious, intelligent. They're fighting for their very
existence. They must have figured out some way of breathing in air, some
way of attacking us on a more even basis in case that first rush went
wrong. What can it be?"

"I think you're borrowing trouble before it is necessary--" I began,
smiling at his elaborate, scientific pessimism. But I was interrupted by
a startled shout from Stanley.

"Professor Martin," he cried, pointing to the tunnel mouth. "Look!"

Like twin snakes crawling up to sun themselves, two tentacles had
appeared over the rock rim. They hooked over the edge; and leisurely,
with grim surety of invulnerability, the barrel-like head of a Quabo
balanced itself on the ledge and glared at us.

* * * * *

For a moment we stared, paralyzed, at the Thing. And, during that moment
it squatted there, as undistressed as though the air were its natural
element, its gills flapping slowly up and down supplying it with oxygen.

The thing that held us rooted to the spot with fearful amazement was the
fantastic device that permitted it to be almost as much at home in air
as in water.

Over the great, globular head was set