"Down, dog! lie still!" Mark listened intently; but there was not a sound to be heard but the distant boom of the breakers on the barrier reef, the beating of his heart, and the growling of the dog.

Once only came a shrill chizzling chirping, evidently made by some kind of cricket, otherwise there was the stillness of a torrid day when the very vegetation begins to flag.
"I can't hear it, sir," he whispered.
"So it can't be coming," said the major, looking uneasy.

"I'm puzzled, Mark.

It was neither lion nor tiger, though something like the roar a lion can give; it was not like an elephant's trumpeting, nor the grunting of a rhinoceros; and it could not be a hippopotamus, for we are out of their range, and there is no big river--there can't be--here." "Could it be some enormous serpent ?" whispered Mark.
"I never heard a serpent do anything but hiss, my lad, though they say the anacondas make strange thunder in the North American forests." "It might be a large crocodile." "Yes, it might," said the major; "but if it was, the noise is something quite new to me." "It is more likely to be some terrible beast here that we never heard of before, sir," faltered Mark.

"Don't laugh at me, sir, I can't help feeling nervous." "You'd be a wonder if you could," said the major.