dle-like sword whose point was razor
keen. Gerry realized the reason for that peculiarly designed weapon when
the sentry swung his sword upward to salute their guide. The blade was
so thin that it offered little resistance to the water, and its power of
being quickly wielded made it a far more effective weapon under water
than a heavier sword would have been.

They passed more branching passages, and more rubber-clad sentries who
stared at them curiously as they went by. There was a whole network of
corridors in this underwater world! At last Slag opened a metal door at
the end of the particular passage he had followed, and they all crowded
into a small room. Slag closed the door and dogged it, then tapped on a
glass panel across the room.

A silvery flood of air bubbles came pouring out the end of a pipe that
protruded through the wall. At the same time Gerry heard the thud of
heavy pumps starting to suck water through gratings at the base of the
wall. The water level dropped rapidly. When it was down to their waists,
Slag took off his helmet and slipped the leaded sandals from his feet.
He motioned to the others to do the same.

"We are about to enter the hidden realm of Luralla, the home of the
Dragon's Teeth!" he said. "If you can prove your right to be here you
will be welcome. Otherwise you will go back into one of these
waterlocks--without any helmets on."

He grinned cheerfully.

* * * * *

The water dropped below the level of the door sills. The pumps sucked
noisily on the last few foaming inches for a moment, and then they
ceased. The inner door was opened by a sentry whose tight fitting green
uniform with its black dragon was made of dry cloth instead of dripping
rubber. He wore a plumed metal helmet, and carried a heavy sword instead
of one of the thin water blades.

"Come in, Slag," he said, "who are these strangers?"

They were in a sort of guardroom, a square chamber where glass water
helmets stood in long rows on metal shelves and many weapons hung in
racks on the walls. The control levers of the pumps were just to the
left of the door. There were half a dozen uniformed men standing about
the room, one of them bearing the silver insignia of an officer on his
chest. When Slag had given a hasty account of the coming of Gerry and
the others, the officer nodded toward an inner door.

"Prince Sarnak has just returned. You will find him in the great hall.
Take these st