He felt that the boat was coming none too soon, for he had been weakened by his immersion beneath the surface, and he found that the effort of keeping upon the surface and holding the girl up was telling on him, despite his wonderful power of endurance.

Already he had begun to fear that he would give out, but the girl suspected nothing of the sort, for he seemed calm and confident.

"I shall owe you my life, Frank," she said.

"We will talk of that later," said Frank, by way of saying something in an unconcerned manner, although it seemed that the effort to speak deprived him of strength.

He looked longingly toward the boat. Two pairs of oars were being used, and the rowers were making the small craft jump with each stroke. The oars flashed in the sunshine when the wet blades came up dripping, and the bodies of the rowers swayed and bent. In the stern somebody waved a cap at Frank and uttered a shout of encouragement.

"Hurry! hurry! hurry!"

It was with the greatest difficulty that Merriwell kept from uttering the words in a wild cry that would have betrayed his failing strength.

He choked it back, however, and smiled encouragingly at Inza.

"They are coming," he said. "In a few minutes we'll be in a boat and quite safe."

"I don't care," she returned, in a significant manner. "They need not hurry."

"If she only knew!" thought Frank.

Once he went down, and the water filled his nostrils so that he strangled a little. Inza gave a cry of alarm, and, fearing she would get excited and struggle, he forced a short laugh.

Nearer and nearer came the boat. He could hear the rump-thump, rump-thump of the oars in the rowlocks.

"Howld on, Frankie, me b'y!" came the cheery call of Barney Mulloy.

"We'll be wid yez in a minute."

Rump-thump, rump-thump-would the boat never reach them?

How heavy Inza was! And it seemed that a great weight was dragging at Frank's feet-a weight he could not cast off.

"Hurry, Barney-hurry!" he tried to cry; but the words died in a hoa.r.s.e gasp in his throat, causing the girl to turn her head to look at him.

"What is the matter?" she asked, in sudden alarm.

"Nothing," he declared, faintly-"nothing at all."

"Oh, I know there is! You are giving out!"

Then he saw she was liable to grasp him about the neck, which would be sure to sink them both, in which case he was certain they would never rise again.

"Don't do it-if you wish to live, Inza," he pleaded. "I can hold you a little longer if you do not touch me; but we shall go down if you grasp me."

She was filled with fear, but something in his words and manner caused her to obey him fully.

Suddenly there was a wild shout of alarm from the boat, and Frank saw Barney making frantic gestures, while he urged the rowers to greater exertions.

Merriwell wondered what it meant. He saw Barney swing his arm and point away toward the channel.

As they arose to the crest of a swell, Frank saw something that sent his heart into his throat.

At a distance the sharp back fin of a shark cut the crest of the water for a single instant and then disappeared.

A shark was coming!

"What-what is it?" asked Inza, who had been startled by Barney's cries.

"Why are they shouting thus?"

"They are doing it to encourage us," said Frank, believing he was fully justified in the falsehood.

"You are sure?"

"Why, of course!"

Rump-thump, rump-thump went the oars! jump, jump plunged the boat as it sped to the rescue.

The rowers were straining every nerve. They were Bruce Browning and Ephraim Gallup, and for once in his life, at least, the big collegian was doing his very utmost. Nothing but an effort to save his own life or that of Frank could have made him work thus.

It seemed that the shark was approaching with the speed of an express train. Fortunately the boat was far nearer, and so it came up first.

Even as the boat shot alongside the youth and maiden, with Bruce and Ephraim backing water to check its headway, there was a flash of a dark body in the water, a flashlike turn, the showing of a white belly, and Barney had dragged Inza into the boat just in time.

Yes, he had dragged Inza in; but Frank-where was he?

He had disappeared!

CHAPTER XII-FRANK IS TROUBLED

Shuddering with horror as he held the dripping girl in his arms, Barney Mulloy looked over the side of the boat, expecting to see the water dyed with a crimson stain.

Browning gave a shout:

"Here he is!"

Frank's head appeared on the other side of the boat.

He had dived just in time to avoid the shark when it turned.

The moment he came up on the other side of the boat Browning and Gallup dropped the oars and grasped him.

They had him in the boat a second later.

The shark had lost its prey.