th a sense of unparalleled
adventure, Larry stood there a moment, peering out over the threshold
of that untrodden world.

Then he followed Diane and her father into its beckoning mystery....

Their searchlights cutting bright segments into the dark, they
proceeded toward the vast mound that towered ahead, pushing through a
weird realm of phosphorescent fish and other marine creatures.

As they neared it, any possible doubt that it was in fact a pyramid
vanished. Corroded by the action of salt water and covered with the
incrustations of centuries, it nevertheless presented unmistakable
evidence of human construction, rising in steps of massive masonry to
a summit shadowy in the murk above.

As Larry stood gazing upon that mighty proof that this submerged
plateau had once stood forth proudly above the sea, he realized that
he was a party to one of the most profound discoveries of the ages.
What a furore this would make when he reported it back to his New York
paper!

But New York seemed remote indeed, now. Would they ever get back? What
if anything went wrong with their pressure-suits--or if they should
become lost?

He glanced back uneasily, but there gleamed the reassuring lights of
the _Nereid_, not a quarter of a mile away.

Diane and her father were now rounding a corner of the pyramid and he
followed them, his momentary twinge of anxiety gone.

* * * * *

For some moments, Professor Stevens prowled about without comment,
examining the huge basal blocks of the structure and glancing up its
sloping sides.

"You see, I was right!" he declared at length. "This is not only a
man-made edifice but a true pyramid, embodying the same architectural
principles as the Mayan and Egyptian forms. We see before us the
visible evidence of a sunken empire--the missing link between Atlantis
and America."

No comments greeted this profound announcement and the professor
continued:

"This structure appears to be similar in dimensions with that of the
pyramid of Xochicalco, in Mexico, which in turn approximates that of
the "Sacred Hill" of Atlantis, mentioned by Plato, and which was the
prototype of both the Egyptian and Mayan forms. It was here the
Antillians, as the Atlanteans had taught them to do, worshipped their
grim gods and performed the human sacrifices they thought necessary to
appease them. And it was here, too, if I am not mistaken, that--"

Suddenly his vibratory discourse wa