Uttering another snort the bulky black sprang to his feet with surprising agility in one of his great size. Harry now let his right hand fall back quickly. He was poising for the throw in earnest, for there could no longer be any doubt that the stranger was planning a deadly assault. "Take it, then, since you want it!" snapped out Harry Hazelton. The fragment of rock left his hand, propelled with force and directed with accurate aim at the negro's face. But the crafty black dodged just in time, at the same instant throwing up his hands. Harry gasped as he saw his unknown assailant deftly catch the rock fragment as though it had been a base ball. "Ha, ha! Ho, ho!" jeered the black, in a hoarse, rumbling voice. He threw back his hand, gathering impetus for the cast. Hazelton could do nothing but throw himself on the defensive, planning to duplicate the black man's catch. Then the stone came---but it did not go high, instead, by a jerk of his wrist, the negro hurled it at Harry's right foot. That granite-like fragment struck Hazelton's foot with full force. "You---you scoundrel!" groaned Harry, in an all but admiring gasp. Like a flash he bent over, snatching up the fragment for his own use. "Now, I'll slam you into the middle of the Gulf of Mexico!" cried the young engineer, vengefully, as he tried to straighten up. A groan escaped him. His injured foot was paining him more than he had expected. "Ha, ha! Ho, ho!" harshly jeered this mysterious, evil creature. The black man had halted as Harry prepared to throw, but he showed no sign of hesitation. Though he stood still, he thrust his repulsive, leering face forward, as though to offer that face as the best mark. Harry found that he could not stand straight---the pain in his injured foot was now too intense. "Get back with you!" ordered Harry. "Get back if you don't want a heap worse than you gave me." "Ha, ha! Ho, ho!" came the sneering laugh. Then the stranger reached out his hands as though to seize the youth. "I guess I'll have to do it---though not because I really want to hurt you!" muttered Harry ruefully. "Ha, ha! Ho, ho!" There could be no question that the unknown was merely playing with him. Little as he liked to make the ugly throw Harry knew that he had to do it. When Hazelton had anything to do he believed in doing it well. So, putting all possible force into his throw, Harry let the rock fragment fly, and this time he was sure that his enemy would not be able to dodge in time. Nor did the black man make any seeming effort to dodge. Bump! Squarely in the black face the rock landed. Harry heard the sound and felt ill within himself. Yet the black man did not stagger. With a contemptuous snort he kicked the fragment of rock into the water as it landed at his feet. "Ha, ha! Ho, ho!"