d with
sharp prow and stern. A compact mechanism and control-board filled
the prow, while at the stern and sides were long tubes mounted on
swivels like machine-guns.

The frog-men motioned Norman and Hackett into one, fastening the two
prisoners and themselves into their seats with metal straps provided
for the purpose. Four had entered the one boat, the others that of the
captives. One at the prow moved his paws over the control-board and
with a purring of power the boat, followed by the other, rose smoothly
into the air. It headed out over the gray-green sea, land dropping
quickly from sight behind, the horizons water-bounded on all sides.
From their nearness Norman guessed that this second satellite of
Earth's was small indeed beside its mother planet. He had to look up
to earth's great gray sphere overhead to attain a sense of reality.

Hackett was whispering beside him, the frog-men watchful. "Norman, it's
not real--it can't be real! These things--these boats--intelligent like
men--"

The other sought to steady him. "It's a different world, Hackett.
Gravitation different, light different, everything different, and
evolution here has had a different course. On Earth men evolved to be
the most intelligent life-forms, but here the frog-races, it seems."

"But where are they taking us? Could we ever find the plane again?"

"God knows. If we ever get away from these things we might. And we've
got to find Fellows, too; I wonder where he is on this world."

* * * * *

For many minutes the two boats raced on at great speed over the
endless waters before the watery skyline was broken far ahead by
something dark and unmoving. Hackett and Norman peered with intense
interest toward it. It seemed at first a giant squat mountain rising
from the sea, but as they shot nearer they saw that its outline was
too regular, and that colossal as it was in size it was the work of
intelligence. They gasped as they came nearer and got a better view of
it.

For it was a gigantic dome of black metal rising sheer from the lonely
sea, ten miles if anything in diameter, a third that in greatest
height. There was no gate or window or opening of any kind in it. Just
the colossal, smooth black dome rearing from the watery plain. Yet the
two boats were flashing lower toward it.

"They can't be going inside!" Hackett conjectured. "There's no way in
and what could be in there? The whole thing's mad--"

"Ther