His musing broke off suddenly and he crouched forward watching intently.  His eyes were staring wide-open and startled at the Wondership.  Its bulk lay blackly against the faint, phosphorescent glow of the black barren.

Then he felt his scalp tighten and his mouth go dry while his heart seemed to stop for an instant and then pound furiously, shaking his frame.

For a second he had seen something that had almost startled him into a cry.  A dark figure was creeping round the Wondership, crouched like an ape as it examined the craft.

The boy had hardly caught a glimpse of it before it vanished, gliding swiftly like an animal into the brush.  Jack rubbed his eyes.

“Am I seeing things?” he asked himself, “but no, I’m positive, as sure as I stand here, that that was a human figure sneaking about down there.  Who could it have been?”

Jack did not sleep much more that night.  The thought that they were not alone on the island was a disquieting one.

CHAPTER XXXII.

THROUGH THE WOODS.

The next morning Jack watched his opportunity, and under the pretext of hunting, left camp after breakfast and made his way to the side of the Wondership.  He wanted to examine the vicinity for footmarks.  But he found none, which was not surprising, for the ground on which the craft had been brought to rest was hard and firm, and not likely to take on any impressions.

In the bright, sunny glow it was hard for the boy to believe that he had actually seen the mysterious figure in the moonlight.  But although he tried to assure himself that he had been the victim of an illusion, and that he had mistaken the shadow of a waving tree branch for a man, Jack knew that he was not laboring under a mistake.  He was certain he had seen rightly; but he decided, for the present, to say nothing to his companions about the events of the night.

Having failed to find any tracks round the Wondership, he started off through the trees on his hunt.  He was traversing a small glade when, in a clump of flowering bushes, he heard a sudden scuffling noise.

Startled, he stopped.  The sound came again and this time it was accompanied by a shrill scream as of some creature in pain.  Jack parted the bushes and made his way through them.  On the other side he came across a rabbit.  The little creature was struggling violently and squealing with the peculiarly human screech that rabbits have when in pain.

The boy saw that it had been caught in some way and could not get away.  Greatly mystified, he dropped to his knees beside it and the next instant solved the puzzle.

The rabbit was caught in a trap ingeniously made from pliable willow twigs and set in a “rabbit run.”  For a minute the full significance of his discovery did not dawn upon Jack.  Then it came like a bolt from the blue.

Somebody on the island, other than themselves, had set that trap!  Perhaps it was the strange, half-ape-like man he had seen by the Wondership the night before.  The boy looked round him in the silent wood as if he half expected to see somebody watching him.