“It’s true enough, my lad. They’ll lay hold on a fellow’s toe or thumb, ay, and on horses too. I’ve known ’em quite weak with being sucked so much night after night.”

“Horses? Can they get through a horse’s thick skin?”

Shaddy chuckled.

“Why, dear lad,” he said, “a horse has got a skin as tender as a man’s, so just you ’member that next time you spurs or whips them.”

Rob sat in silence, thinking, with the weird sounds increasing for a time; and, in spite of his efforts, it was impossible to keep down a shrinking sense of dread.

Everything was thrilling: the golden-spangled water looked so black, and the darkness around so deep, while from the Grand Chaco, the great, wild, untrodden forest across the river stretching away toward the mighty Andes in the west, the shouts, growls, and wails suggested endless horrors going on as the wild creatures roamed here and there in search of food.

Plash! right away—a curious sound of a heavy body plunging into the river, but with the noise carried across the water, so that it seemed to be only a few yards away.

“What’s that?” whispered Rob.

“Can’t tell for sartain, my lad, but I should say that something came along and disturbed a big fat ’gator on the bank, and he took a dive in out of the way. I say! Hear that?”

“Hear it?” said Rob, as a creeping sensation came amongst the roots of his hair, just as if the skin had twitched; “who could help hearing it?”