Gone--both of them, said Brace, laughing, as he lowered the hammer of his piece, for the sea-cow suddenly gave a wallow and went down with a loud splash as if it had been alarmed by the sight of something approaching, while its disturbance of the water acted upon the great alligator, which sank at once, startling another, of whose presence the watchers were not aware till they caught a glimpse of the reptile's tail as it disappeared.