As he did so, he paused, in wild apprehension. The pump-strokes had ceased! Then he grinned, with a sigh of relief; of course Bob would have had to quit work in order to get the body of Jerry over the landing, and unscrew his helmet so that air might reach him. When the pump-strokes began again, he could go up.

Mart glanced around curiously. The hold of the ancient ship was dark, and he could see nothing, for the light down here was dim, rendering all things distorted and indistinct; this his thick glass-plates did not tend to help, but a moment later he became aware of something like a box that protruded on his right, and remembered what Jerry had said about a chest of treasure being in sight.

He had sheathed his knife while sending the quartermaster up, and now he drew it and shoved the blade against the box. It seemed of great weight, for even in the water it did not move under the shock. Then he kicked it with his heavy boot, and saw it shake and shatter. The wood must be pretty rotten, he reflected, and with that he kicked it again.

"Well, I'll be switched!" he gasped, starting back. Not only had the box gone to pieces, but pouring out from its shattered corner came a stream of gold coins! That they were gold he did not doubt for a moment; even in the semi-darkness they gleamed and shone ruddy yellow, pouring out and out until they covered even the high soles of his diving boots.

"Thunder! I've struck it!"

For a moment he stared down, unable to move. Then he felt a little wave of pure air sweep around his face and heard the pumps begin to click again up above; until then he had not realized that his air was becoming vitiated. But he paid no attention to anything but the stream of yellow coins that were settling down over his feet, and neglected the fact that now he could ascend.

Gold! With the word ringing through his brain Mart leaned over cautiously, so as not to lose his balance, and stirred the heap of coins with his fingers. He wanted to take some of them up, but had no pockets. Going to his knees, he began to stuff the coins wildly under his belt, under the broad straps of his shoes, even forcing some beneath the weights of his chest.

While he was doing this, he suddenly felt tug after tug on his line—frenzied pulls that woke him from his gold-fever instantly. What was wrong? He answered with one "all right" signal, but still the tugs continued, at both lifeline and air line. Concluding that he had best ascend, in any case, he cautiously emerged from the opening until he once more stood outside the wreck.

He put out his hand toward the kris, meaning to take it up with him; then his heart seemed to stop beating and he stood frozen with horror. What was that dim, vague shape sweeping past, up above?

Mart stood gazing upward, unable to move as the realization of his terrible position flashed on his mind. The long, tapering shadow told its message only too clearly. The Pirate Shark had returned—and he was trapped! Now he understood the meaning of those frantic tugs. Bob had seen the shadow and had tried to warn him. Too late!

With a groan of agony, Mart drew back into the opening. He remembered what old Jerry had said—that so long as a man had his back to something, kept on his feet, and had a weapon, he was all right. Therefore, he must not try to go up, for then the shark could grab him with ease.

Cold sweat stood out on his forehead. What was it Jerry and the others had said about the Pirate Shark always nipping the air hose first? Poor Mart trembled as he still stared up, in hope that the shark might have flitted past and would not return. Again came Bob's frantic tugs, and on a sudden Mart felt calmness flood into his brain, and he reached for his air hose.

"By golly, I've got a fighting chance and that's all!" he muttered, then his lips clenched.

He pulled the air hose twice, then twice again, with the signal for more air. He repeated it, for he knew now what he must do. To attempt going up was impossible; the shark would cut his line, and then come down to finish him. Therefore he must get all the air possible—

"Ah!"

A little click behind his ear, and the noise of pumps stopped. A flicker of the dim gray shape above, then it became larger, more firm of outline. Down through the water curled the air hose and lifeline, bitten through, and Mart had a vision of the tremendous fish as it flitted past overhead, turning in a great curve. The sight was paralyzing. Then Mart gripped the kris, tore it from the barnacled wood, and whipped around to meet his enemy. He had no way of getting up to the surface, his air-supply was limited—but he would not give up without a struggle.



CHAPTER XVI

THE BATTLE

When he gained a full and nearer sight of the Pirate Shark, Mart's courage all but failed him. For a moment the gigantic fish seemed to hang poised in the water above and beyond him, some twenty feet away; what its actual size was Mart could not guess, in the dim and blurred light, but there could never be another such shark as this in all the oceans!

Huge, cruel-eyed, with its mouth showing as he looked up at it, Mart never forgot the horror that seized him at his first face-to-face meeting with the Pirate Shark. He thought of a thousand things in that one moment—the uncanny cunning of the terrible fish in first cutting him off from all help by biting through his lines, poor Bob waiting up above in agonies of suspense, and above all, the awful fact that unless he conquered quickly, he would suffocate.

Still the shark hung poised above him, the immense body motionless except for the gently-waving fins and tail. The big dorsal fin was hidden from him, so he could not see whether it had been pierced by the bullet or not. But he must act, and act quickly! What should he do?

In order to get at the monster shark with the kris, he would have to expose himself. If the brute was cunning enough to cut his lines, he would be too wise to attempt an attack while Mart stood in the wedge-shaped opening of the wreck. There, he could not reach the boy, and would realize it.

Mart wasted no time in hesitation. He was running a terrible risk, for once the shark butted into him or struck him with its tail, he would be flung off his balance and would be lost. But remembering his great lightness in the water, remembering how easily he could leap out of danger, he stepped forward confidently from his shelter, the kris held ready.

No sooner had he done so than the shark began to move. Gradually, with a terrible slowness, the huge shape came forward; the impulse to leap back to shelter was horribly strong, but Mart resisted it.

Around circled the shark, exposing its full length. Mart trembled at the sight, for it seemed to him that the brute must be far longer than the thirty feet which Jerry had assigned as its size. It stretched out quivering in the depths, ghostly, ominous; and most terrible of all was the silence that prevailed over all things. Mart wanted to shout, to yell for aid, and could not.

Almost without warning, the great bulk swept around and came at him, twisting about so that the gaping mouth could nip him as it swept past. But Mart was ready; every nerve and muscle in his body was tensed up to the highest pitch, and as the shark lunged forward, he swerved sharply back to his shelter.

None too soon, indeed. The gray bulk swept down on him in a great swirl that almost flung him off his feet; as he reeled, catching at the corner of the wreck for support, he saw the rough, mottled skin shoot past hardly a foot away. Mart swiftly jerked up his kris and lunged forward with all his strength.

He felt the keen weapon shear into the brute and jerk him out, but he grimly held to his grip. Something struck him and sent him staggering; then he had pulled the kris free. Barely had he done so when the shark's huge forked tail drove past his head in a lash of foam and blood, and Mart reeled back into his shelter. The sides of the wreck caught his shoulders and kept him upright, fortunately.

He noticed a slight roaring in his ears, and knew that the air was beginning to get bad in his helmet. He pressed his diving dress and forced up some of his remaining supply. Peering out, he could not repress a thrill of exultation—he had won the first round!

Yet it was a strange and awe-inspiring sight that met his gaze. Tingeing the water a dim red, the immense fish was tearing to and fro in wild fury, lashing across the entrance like lightning, drawing the water in swirls and whirlpools that came near to dragging out Mart despite his grip on the wreck. He felt even the old ship tremble beneath the fierce blast of water, while the huge gray shape flashed down and across and up, back and forth, in terrible spasms of rage. But after it trailed that thin stream of red, and Mart exulted.

"By golly, I've got to finish this thing quick!" he thought vaguely, for the roaring in his ears had increased, and it was hard to fill his lungs with the vitiated air. "If I can only settle him, I can cut off these weights and take a chance on shooting up to the top. It'll be a mighty slim chance, but it's all I've got."

Rendered desperate by his fear of suffocation, which was even greater than his fear of the Pirate Shark, he advanced to the edge of the opening with a resolute determination to take any chance that offered. Nor was it slow in coming.

Down swept the shark with a rush, flicking in its tail as it passed, and Mart leaped back only just in time to avoid it. But he saw the brute's purpose now—to try to suck him out with the swirls of water, or to strike him over with its tail, and as he eyed the dim gray shape that was circling around for another rush, he made ready. He must strike as the huge body flicked past—and he must leap back before the tail could get to the opening!

That meant only one thing. He would have no chance to pull out his kris this time. Everything would depend on the one sure stroke, which must be a death-wound. If not, the kris would be carried off in the shark's body, and with his little sheath knife alone left him, he would be helpless.

"Got to do it!" he thought dully, for now his ears were paining, and he began to feel as if his nose were about to bleed. He was gasping for air, and forcing up newer air from about his legs and body only relieved him slightly. "Got to do it this time, or lose out!"

All the water seemed faintly hued with crimson now, and he knew that his first blow must have worked considerable damage. The shark had dashed off until he could only see it dimly—a monster shadow that darted smoothly but erratically about in the distant depths, as if working itself up to a greater fury. Then it swung about in one wide sweep, and began to grow plainer as it came down upon him.

Its speed was appalling. During his instant of waiting, Mart's courage almost failed him; it seemed impossible that he could strike and leap back in time to avoid the flashing tail!

Nor could he, as it proved. The monster fish drove in upon him, turning as it came, its bulk seeming to fill all the space above and to crush him back upon the wreck; then Mart, never giving an inch, shoved his flame-bladed kris forward, saw it go home to the hilt in the gaping mouth of the Pirate Shark, and then was swept from his feet.

He went down with a rush in the tremendous swirl of waters, being drawn along the side of the wreck for a little space; but the fall proved to be his salvation. As he struggled feebly and vainly to gain his feet, he could see that everything was gone crimson around him. Through the bloodstained waters lashed the whiplike tail of the Pirate Shark, beating with terrific force against the wreck; the fish, blinded by its own lifeblood, was trying to find its enemy, and a single stroke from that tail would have finished Mart forever.

He lay quiet, huddled against the wreck, but now there was little fear of the Pirate Shark in his heart. Whatever the results of that final blow had been, nothing now mattered except the terrible pains that had come upon him. The air in his helmet seemed to poison him, his throat and lungs were on fire, and he knew that he was bleeding at the nose.

"By golly, this is awful!" he muttered thickly.

He determined not to give up without a last struggle, however. He still had his sheath knife, and he could cut away his weights and shoot up. Though it would be dangerous, both because of the pressure and because of the Pirate Shark, he spent no more thought on it but drew his knife and tried to rise.

This was no easy matter, so evenly was his weight adjusted, but he finally managed to get up, leaning weakly against the side of the wreck. His head was buzzing madly, and it was difficult for him to see anything because of the cloud of blood and stirred-up slime that filled the water.

He could see nothing of the Pirate Shark, but that did not matter now. Managing to get out his knife, he tried to stoop over and cut away his shoes. To his terror, he lost balance again and fell weakly forward, unable to stop himself. He was gasping and fighting for breath now, but there was no good air for him to breathe. He felt dimly that he was gone.

He had no strength; still he fought up to his feet once more, savagely determined not to give in to the suffocation, trying vainly to rid himself of the helmet. But he had dropped his knife, and dared not stoop for it for fear he could not regain his balance.

Suddenly something flickered across the glass window, and he gasped out a broken laugh, thinking it a snake. Snakes would trouble him little, after battling with the Pirate Shark! But was it a snake? It stayed unaccountably still; then it began to jerk forward and back most strangely, switching against the glass before his eyes. He put out his hand and touched it—rough hemp! Then he saw that a piece of metal was fastened at the end, and was bumping against his legs. It was a rope.

"Good old Bob!" he thought, as a momentary wave of coherence restored his brain to itself for an instant. "I've got to fasten it—don't believe I can hold on very long!"

However, the trailing end of his own life line was still attached to his belt. Hauling it in, he managed to get the two lines knotted, then gave the four pulls to "haul up!" He perceived the line tighten immediately, when a terrible gasping for air seized him and shook him; he tore at his diving suit with his hands, a spasm of agony making him reckless whether he let in the water or not. But fortunately the rubber-cloth was stout.

His frantic efforts had exhausted what little oxygen was left to him. He knew faintly that the wreck had seemed to drop away from him, that he was swinging up through the water—and just as the water seemed to be growing lighter, everything went black before his eyes, there was a rush of stars, and he knew no more.

Up above on the landing, Bob was pulling away desperately, with fear in his heart. At one side lay the figure of Jerry, still in diving dress but with helmet removed. The old quartermaster lay very still and white, but Bob had no chance to work over him. When Mart's line had parted and that terrible shadow had appeared down below, Bob had almost given up. Then he had leaped into energy, for he knew that now Mart's life depended on him alone.

He had swiftly cut away Jerry's back-weight and attached it to a line, which he lowered, swinging it back and forth in the hope that Mart would see it. The under-water battle had lasted only for two or three minutes, although it had seemed an age to poor Mart, and now Bob was hauling up with all his energy. He had seen the dim shadow shoot off, leaving a great trail of blood, and he knew that Mart must be hard pressed for air; as he pulled, he prayed that the shark would not return until his friend was safe.

With a sob of relief, he caught the flicker of the copper helmet in the water, and finally got the limp form to the surface. Pulling Mart in was a hard matter, but it was finally accomplished, and Bob fell on the helmet and unscrewed it with trembling hands. Mart's bloody face and ghastly pallor struck him with cold fear, but he went to work at once to drive air into the contracted lungs, hoping against hope.

How long he worked over the unconscious figure he never knew. He shouted again and again for Ah Sing, and when at length the affrighted Celestial appeared at the top of the ladder, Bob sent him for some stimulant. Ah Sing vanished, and a cry of joy broke from Bob's lips, as he saw a faint color come into Mart's face and ebb out again. Mart was alive!

Bob labored furiously, and when Ah Sing showed up with a bottle of alcohol, he said nothing but rubbed Mart's face and neck with the fiery liquid. Presently he was rewarded by a twitch of Mart's eyelids, a little more color came into the faded cheeks, and then the gray eyes opened and looked up into his.

"Look out—he's coming!" whispered Mart, his hand going up and clutching Bob's arm.

"It's all right, old boy," cried Bob, tears running down his cheeks with the relief that gripped him. "You're safe—take it easy!"

Up above them, Ah Sing burst into a frenzied chattering, then rushed away, but neither boy noticed him. Mart lay motionless, looking up into Bob's eyes and slowly feeling strength come back to him as the reviving air found its way into his lungs.

"I got him, Holly," he gasped weakly. "Did you see him?"

"Sure!" returned Bob. "Keep quiet, now. Don't try to talk. You're not hurt, are you? Nothing more than the air?"

Mart shook his head. After a moment he managed to sit up with Bob's assistance, and saw the motionless form of Jerry. Before he could speak, Bob restrained him.

"I haven't had time to look at him yet, Mart. I—I guess I feel kind o' weak myself—"

"Seamew ahoy!" came a hail. "Where are you, Bob?"

"By juniper!" gasped Bob, jumping up. "It's dad!"



CHAPTER XVII

THE MYSTERY O' THE SEA

As around the stern of the Seamew came a prau, Ah Sing shrieked aloud in delight and the boys gave a hearty cheer at sight of Captain Hollinger and Swanson standing in the prow of the craft. Beside them stood the two engineers, while the Kanaka crew of the yacht were at the sweeps.

"By golly, they got away!" gasped Mart, managing to scramble to his feet. The sight of the motionless figure of Jerry Smith sobered both boys, however, and while Bob stepped forward to meet his father, Mart kneeled down beside Jerry with feeble efforts to revive him. His own strength was not yet fully returned.

"What's all this?" demanded the captain, as he leaped from the prau to the landing. "Where are those mutineers, Bob?"

"Ashore, all but Jerry," returned Bob promptly, pointing to the quartermaster's figure. Captain Hollinger waved back his men and joined Mart. After a cursory examination he rose to his feet and pulled Mart up also.

"No use, boys," he said softly. "Jerry has found the mystery of the sea at last. Now come along. Tell me what's been going on here."

Mart was unable to speak for a moment, but startled as Bob was, he replied with another question, as Captain Hollinger drew them both up the ladder to the deck.

"Tell us how you got away, first. We thought the Malays had you!"

"So they did," grimaced the captain, "until that assistant engineer came ashore with the Kanakas. Before they got him into the river he had impelled the Kanakas to capture the prau. Then he got his irons cut off and led the Kanakas straight up to the village. I was just starting for the hunt, in blissful security, when he broke in on us and told us what was up. As the Kanakas were armed, the Malays had to give in gracefully—and here we are. Now come across, you boys!"

Naturally, his wonder was great at finding Mart and Jerry in diver's dress, the old quartermaster dead, and Bob looking pretty shaky. Bit by bit the boys told their tale, and only by an effort could they realize that so many things had happened in this one day, for it was not yet sunset.

While they were talking, Swanson joined them with word that Jerry must have died from heart failure, not from suffocation; no doubt the shock of finding himself cut off had stricken him. But Captain Hollinger and his first mate forgot all else in their amazement at Mart's story of the fight eight fathoms down. In fact, Mart saw plainly that they did not believe him and thought that the descent must have shaken his mind.

With that he pulled off the diving costume, which as yet he had had no chance to remove. When they had helped him out of it, and three or four gold pieces fell to the floor, all incredulity vanished. Bob, Mart and Swanson crowded around the captain, examining the coins with wild excitement.

"Well, I'm bound to say that your story and Jerry's yarns seem to be substantiated, boys!" exclaimed Captain Hollinger. "These seem to be old Spanish or Portuguese coins—they coined them out here then, you know. And here's the date—1632. Yes, they all have the same date. By Jove, Mart, you've made a haul here!"

The boys stood silent, and Swanson pawed over the gold pieces with a flame in his eyes until Captain Hollinger had switched up the electric lights, for the sudden night of the far east had fallen. Then the mate abruptly pushed the coins across the table, and faced the captain, breathing heavily.

"Cap'n Hollinger," he said, with a visible effort, "when you took me on you knew that I'd had a more or less shaky kind o' past, didn't you?"

"Eh?" The captain flung him a keen glance. "What do you mean, Mr. Swanson?"

"Just this, Cap'n. Once, when I was a fool young fellow, I got mixed up wi' old Jerry. He was a trader among the islands then, nothin' short of piracy it was in them days. When he come aboard this yacht, wi' them four men out o' his old crew, I knowed there was trouble brewin'. He finally told me about this here treasure, and how he was a-goin' to take the yacht, and wanted me to join him. I warned him off, Cap'n, and I was fool enough to think he'd take the warnin'. But he didn't. Now that it's come out right, I wanted to get it off'n my conscience, that's all."

Captain Hollinger reached across the table, and gripped Swanson's hand.

"Mr. Swanson," he said, smiling, "I'm proud of you. Your wages are doubled this trip—no, no protests, please! Evidently Jerry led me astray all along, and the only gold in this lagoon was the treasure. Now I think you'd better take the deck, Mr. Swanson."

"Yes, sir," replied Swanson humbly, his eyes gleaming oddly. "And what about them four men on the island, sir?"

"Let them go, Swanson. They'll get food from the Malays, and they can easily make their way to Singapore in the boat. I'll not prosecute them. As for Jerry, we'll bury him in the morning."

Swanson lumbered out of the cabin. Captain Hollinger turned to Mart, and asked him to go over his fight with the Pirate Shark in more detail. Mart did so, for by this time he had recovered entirely except for a shakiness in his legs. The captain listened to the story silently, then nodded.

"I'm pretty sure you finished off the brute, Mart. That finishing blow of yours seems to have driven in the kris either through his throat or else through his mouth to the brain."

"But you didn't see anything of the body as you came?" asked Bob anxiously.

"No. He'd probably not rise until to-morrow, in any case. I've no doubt, however, that we'll find his body to-morrow or next day, boys. What a trophy his skin would make, eh?"

"Could we have it mounted, dad?" queried Bob.

"Too big," retorted Mart practically. "The only place it could be used would be in a museum, Holly."

"Well, why not?" smiled the captain. "It would be a welcome addition to any museum, Mart, and our Kanakas can take off the skin in a few hours. And think—after it's mounted and set up, you'll see your name on the bottom—killed and presented by Mart Judson! How's that?"

"Pretty good," grinned Mart. "But say, let's get down to solid earth, Cap'n. Are we going to get after the rest of that treasure down there?"

"Are we?" retorted the captain. "Surest thing you know, Mart! We'll bury poor old Jerry to-morrow morning, and in the afternoon we'll send down a couple of the men, when we've made sure that the Pirate Shark is out of the way. And if there's as much of the stuff as you say you saw, Mart, you'll have a good stake to—"

"Hold on," interrupted Mart, surprised. "You seem to think that I'm trying to grab it all, Cap'n. I didn't mean to—"

"Of course you didn't," laughed Captain Hollinger, stretching out easily in his chair. "But I'd like to know who else the gold belongs to, Mart. You've won it by right of conquest, seems to me."

"That's right," added Bob hastily. "It's all yours, old boy. You fought for it, and you ought to—"

"Now look here," and Mart leaned forward earnestly, with his air of determination. "That's not right. I'd never have got up if it hadn't been for Bob, Cap'n. We're in on this thing as partners, and when we get that treasure we're goin' to split on it, or Mart Judson isn't goin' to touch any of it. Now, that goes."

There was no doubt that he meant his words. Bob, however, still attempted to protest, but Mart promptly shut him up.

"None of that, Holly. I guess there's enough treasure there to satisfy us all, and my end of it is going for an education. That's all I have to say."

"Then that settles it," laughed Captain Hollinger, rising at the sound of the gong from the mess saloon. "Ah Sing has mess ready, and I'm famished. Come along, boys, and we'll all feel better after a bite to eat."

He led the way out, but at the door Mart stopped his chum.

"I forgot to thank you, Holly," he said quietly. "I won't forget that it was you pulled me up, old man. And when we mount the Pirate Shark, our names go on that brass plate together!"

And Bob grinned happily as they struck hands.

THE END