“What! do you think? Oh, I see now! How horrible!” said Mark.

“Horrible, eh?” grunted Gregory. “I wish they’d make a day of it, and eat one another all up. We could get on very well without sharks.”

Mark said no more about putting their enemy out of his misery, but sat watching till, at the end of a few minutes, the surface of the lagoon grew calm; but until they had turned a low spit of sand, the black fins of at least a dozen sharks could be seen cruising round and round, and to and fro, in search of something more to satisfy their ravenous hunger.

“We are getting some experience of the dangers we shall have to encounter,” said the captain, as the scene of their late conflict with the shark passed completely out of their sight, and they rowed on steadily. “That’s your first shark, Mark, eh?”

“Yes,” said Mark, thoughtfully, “I shall know what a shark is now.”

“I think we’ll give them a turn now, Gregory,” said the captain. “No, no, one at a time,” he cried angrily, as the men sprang up together. “We must not capsize the boat here. Now you, my man,” he continued, sitting fast, as the sailor stepped across and took the mate’s place before Mr Gregory rose. “Now you, Widgeon.”

Billy crept very softly into the captain’s place, and the latter seated himself on the thwart in front of Mark, to be joined directly by Gregory.

“There,” cried Mark, as the oars dipped, “I heard it. There.”

“What?” said his father.

“That roaring which Mr Gregory heard.”