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.