the sea. The
great low cavern, without the support of the myriad walls, would
probably collapse--trapping the invading Quabos and leaving the rest
without a home once more.

But Aga answered this before I could voice it.

The Quabos had foreseen that point. They were tunneling slowly but
surely toward the city from a point about half a mile from the diving
chamber. And as they advanced, they blocked up the passageway behind
them at intervals, drilled down to the great underground sea that lay
beneath all this section, and drained a little of the water away.

* * * * *

In this manner they lightened, bit by bit, the enormous weight of the
ocean depths. When the city was finally reached, not only would it be
ensured against sudden destruction but the Quabos themselves would have
become accustomed to the difference in pressure. Had they gone
immediately from the accustomed press of Penguin Deep into the
atmosphere of Zyobor, they would have burst into bits. As it was they
would be able to flood the city slowly, without injury to themselves.

"Now thou knowest our fate," concluded Aga with a shudder. "Zyobor will
be a part of the great waters. We ourselves shall be food for these
monsters...." She faltered and stopped.

"But this cannot be!" I exclaimed, clenching my fists impotently. "There
_must_ be something we can do; some way--"

"There is nothing to be done. Our wisest men have set themselves
sleeplessly to the task of defence. There it no defence possible."

"We can't simply sit here and wait! Your people are wonderful, but this
is no time for resignation. Send for my two friends, Aga. We will have a
council of war, we four, and see if we can find a way!"

She shrugged despairfully, started to speak, then sent in quest of
Stanley and the Professor.

* * * * *

They as well as myself, had had no idea of the menace that crept nearer
us with each passing hour. They were dumbfounded, horrified to learn of
the peril. We sat awhile in silence, realizing our situation to the
full.

Then the Professor spoke:

"If only we could see what these things look like! It might help in
planning to defeat them."

"That can be done with ease," said Aga. "Come."

We went with her to the gardens and approached the nearest pool.

"My fish-men are watching the Quabos constantly. They report to me by
telepathy whenever I send my thoughts their way. I will let y