The American lad was as lively as a cricket, and busy thoughts surged through his brain. In the first place, he did not propose being a target for a Spanish bullet. But, above all, he wanted that boat, and, like the cowboy when he wants a revolver, wanted it "bad." "How can I get it?" he thought, as his dive brought him up near the bow of the boat. Help came from an unexpected source, for a few moments after, he was driven by a new peril to attempt the only plan that could accomplish it. The agency that led to his delivery was a shark. That was not the every-day business of his shark-ship--that of saving an imperiled life for those inhabitating those waters are especially hungry and voracious. But it happened this way: As Clif was quietly keeping himself afloat at the bow of the boat, confident that in that position he ran little risk of immediate discovery by his enemies, the plans and schemes revolving in his mind were brought to a sudden standstill by a sight that filled him with horror. A sharp triangular fin cutting the water like a knife, flashed past him. "Merciful Heaven!" he muttered under his breath. "A shark!" Death faced him on every side. To be sure he might frighten the shark by churning the surface of the water, but that very act would betray him to a no less certain death at the hands of his enemies. His resolve, a desperate one that caused him to shudder as he formed it, was reached on the instant. The broad back of his enemy, who sat in the stern, was within easy reach, and inspired his action. Quick as a flash Clif grasped the stern of the boat with one hand and with one mighty effort raised himself high out of the water. Before the Spaniard could divine what was happening, Clif's free arm was thrown around the fellow's neck, and he was drawn back into the water behind him. An instant after Clif clambered over the stern into the boat. With a shudder at the thought of the fate that awaited the luckless Spaniard, he addressed himself to the work that lay before him. And there was plenty of it, and lively, too, while it lasted. The other Spaniard, who had been peering into the water ahead, turned sharply around when he heard the noise made by the splash of his companion, and in the act involuntarily dropped the revolver. What must have been his feelings upon beholding the lithe and dripping form of the plucky young American emerging from the sea, may well be imagined. But Clif did not pause to study the effects. He seized an oar and sprang toward his remaining foe. "Surrender, you villain!" he cried in Spanish as he advanced. The Spaniard seized an oar and with an oath sprang toward the American. And there, on the quiet bosom of the water in the dim light of night, ensued a stubbornly contested duel, in which oars took the place of broadsword and sabre. Clif fought savagely and desperately. His blood was up, and he knew that now, if ever, he was, fighting for his life.