They looked intently on it, then Arthur said, "This shell has undoubtedly been roughly cut from the animal. The important question is, who cut it?"
"Perhaps the crew of the wrecked vessel," suggested Hugh.
"It may have been so," answered Arthur, somewhat relieved.
Then O'Brien shouldered the large shell, and they moved forward thoughtfully for a few minutes; till a dark spot at some distance from the water attracted the attention of Arthur; they hastened towards it, and saw to their great consternation, not only the traces of a recent fire, but the naked footmarks of men, the head of a turtle still bloody, a long wooden spear, plainly hardened by fire, and an instrument which Arthur recognized from description to be a throwing-stick for the spear, as it had a hook at one end which fitted a notch at the heel of the spear, which the holders were thus enabled to project with great force.
"We must carry away these curious arms," said Hugh.
"Certainly not, I think," replied Arthur. "In the first place, we have no right to take them, since they have been left here in good faith, as we might have left our spades in our own grounds at home; and next we should thus place ourselves in the position of invaders and marauders, and incur the enmity of dangerous foes. We had better obliterate all traces of our visit, and, like prudent fellows, retreat quietly."
"Run away! Arthur," exclaimed O'Brien. "You may as well speak plainly. And won't Margaret think us a set of poltroons?"
"We will talk of that as we retreat," said Arthur, laughing; "but we must carefully examine the way we came, that we may leave no footsteps."
As it happened, the vivacity and restless curiosity of the boys had induced them to keep close to the cliffs, leaping from rock to rock, peeping into crannies for nests, so that no traces were left, except where the tide would soon wash them away, and Arthur resolved now to ascend the cliffs at once, instead of going round the island, to escape any risking of meeting the savages. He calculated that they had reached a part of the shore nearly opposite to that on which they had first landed; and by directly crossing the island, which he felt could not be more than three miles over, they might safely and speedily rejoin their friends.
"I do not think it probable," he said, "that this barren island has any permanent inhabitants. The people who have left their traces on the coast may come over from some more productive soil, solely to catch the turtles."