And you had better stop too, Merwell!"

"Don't yo-you shoot at us!" screamed Link Merwell, in sudden terror.

And then he ran with all speed for the nearest trees and dove out of sight. The next instant Jasniff disappeared, likewise.

Dave was now thoroughly aroused, and he resolved to do his best to run the rascals down and corner them. Shifting his shotgun once more to his back, he ran on in the direction the pair had taken, and Roger, Phil, and the captain and the Englishman followed.

Listening occasionally, they could hear Jasniff and Merwell crashing through the undergrowth and at the same time calling to each other.

Evidently they had become separated and were trying to get together again.

As they advanced into the forest, Dave caught sight of Merwell. He was behind a low fringe of bushes and an instant later disappeared.

"Stop, Merwell!" he called out. "It won't do you any good to run. We are bound to catch you, sooner or later."

"Yo-you let me alone, Dave Porter!" spluttered Merwell. He was almost out of breath, so violent had been his exertions.

Dave kept on and soon reached the low bushes. Then he saw Merwell again, this time leaping for some brushwood between two tall rocks.

"I've got you now!" he said, sharply. "You may as well give in!"

"Oh, Porter, please let me--" commenced Link Merwell, and then Dave's hand caught him by the shoulder and whirled him about.

As this happened something else occurred that filled both pursued and pursuer with alarm. The gra.s.s and brushwood under their feet began to give way. Then of a sudden Link Merwell sank from sight, and Dave disappeared after him!

In the meanwhile Phil and the others kept on in the direction Nick Jasniff had taken. Twice they caught sight of the former bully of Oak Hall, but each time he was further away than before.

"You'll not catch me!" cried Jasniff. "You might as well give up trying." Then he dove into another section of the forest and they saw no more of him.

"What has become of Dave?" asked Phil, when he and Roger came together, a little later.

"I thought he was with you, Phil."

"And I thought he was with you."

"He went after that other chap," put in Captain Sanders. "Perhaps he caught him. They were over in that direction," and the captain pointed with his hand.

All proceeded in the direction indicated. But they did not catch sight of either Dave or Merwell.

"Well, this is strange, to say the least," remarked Phil, after they had called out several times. "What do you make of it, Roger?"

"I'm sure I don't know, Phil. They can't have gotten so far away but what they could hear us call."

"Maybe they fell into one of the caves," suggested Captain Sanders.

"If they have, we had better hunt for Dave at once," returned Roger.

CHAPTER XXV-LINK MERWELL'S STORY

Down and down and still down went Dave, with Link Merwell in front of him. Daylight was left behind with a suddenness that was appalling.

The brushwood scratched our hero's face and he could not repress a cry of alarm. Merwell screamed loud and long and an echo came back that was weird and ghostlike. Then came a mighty splash, and both boys went into the water over their heads.

Dave was a good swimmer, and as soon as he entered the water he struck out to save himself. He came up in almost utter darkness, so he had to go it blindly, not knowing in what direction to turn. Then he heard a wild spluttering and knew the sounds came from his enemy.

"Merwell!"

"Oh, Porter! Sa-save me, please!" gasped Link Merwell.

"Why don't you swim?-that is what I am doing."

"I-I-struck my head on a rock! Oh, save me!" And then came a gasp, and the scamp disappeared under the surface.

Dave was close by and knew the direction by the noise. Taking a few strokes, he b.u.mped into Merwell, who promptly tried to catch his would-be rescuer by the throat. But our hero was on guard and turned him around.

"Keep quiet, or I'll let go!" he ordered, as he began to tread water.

As Merwell obeyed, Dave struck out to where he saw a faint streak of light. He made out a shelving rock, and after some difficulty, reached this. Here the water was only up to his waist, and he waded along, half carrying his enemy, until they reached another series of rocks, where both crawled up to a spot that was dry. From somewhere overhead came a faint streak of light, testifying to the fact that there was an opening beyond, even if it could not be seen.

"Oh, my head!" murmured Link Merwell, and put up one hand to a lump that was rising on his forehead.

"I got struck myself," said Dave. "But it didn't amount to much. I told you to stop. If you had done so, we wouldn't have gotten into this pickle."

"Whe-where are we?" asked Merwell, and there was a shiver in his tone.

"Down at the bottom of that hole." Dave tried to pierce the darkness.

"Looks like some underground river to me."

"The water is salt."

"Then this place must connect with the ocean." Dave drew a deep breath. "Merwell, tell me truthfully, what did you do with those jewels?" he questioned, eagerly. Even in that time of peril he could not forget the mission that had brought him to Cave Island.

"Who-who said I had the jewels?" faltered the other.

"I know you and Jasniff took them-it is useless for you to deny it."

"How do you know that?"

"Never mind now. Answer my question. Have you the jewels, or did you give them to Jasniff?"

"I didn't give Nick anything."

"Then you have them."

"How do you know?"

"I am not here to answer questions, Link Merwell. I want to know what you did with the jewels." Dave's voice grew stern. "Answer me at once!" And he caught Merwell by the arm.

"Don't-don't shove me into the water!" cried the scamp, in alarm, although Dave had no intention of doing as he imagined. "I-I-we-er-we divided the jewels between us. But Nick got the best of them."