The Centaurian quickly drew a slender tube of dark green from a scabbard in its belt. Dixon dodged back, looking wildly about him for a weapon. There was an ax in the pile only a few yards away. Dixon snatched the ax up, and whirled to give battle. * * * * * The other Centaurian had come hurrying over now to aid its mate. Dixon was effectually barred from attempting any progress toward the projectile by the two grotesque creatures as they stood alertly there beside each other with their green tubes menacing him. Dixon waited tensely at bay, remembering those searing radium burns upon Emil Crawford's body. Then the first Centaurian abruptly leveled a second and smaller tube upon Dixon. A burst of yellow light flashed toward him, enveloping him in a cloud of pale radiance before he could dodge. There was a faint plop as the protecting white globe upon his head was shattered. The yellow radiance swiftly faded, leaving Dixon unhurt, but he realized that the first round in the battle had been won decisively by the Centaurians. His only chance now, was to end the battle before the paralyzing rays of the green moon sapped his strength. He warily advanced upon the Centaurians. Their green tubes swung into line and twin bolts of violet flame flashed toward him. He dodged, and the bolts missed by inches. Then Dixon nearly fell as his foot struck a bundle of cloth on the ground. The next moment he snatched the bundle up with a cry of triumph. It was his lead-cloth tunic, torn and useless as a garment, but invaluable as a shield against the searing effects of those bolts of radioactive flame. He hurriedly wrapped the fabric in a rough bundle around his left forearm. The next time the tubes' violet flames flashed toward him he thrust his rude shield squarely into their path. There was a light tingling shock, and that was all. The bolts did not sear through. With new confidence, Dixon boldly charged the two Centaurians. A weird battle ensued in the garishly lighted arena. The effective range of the violet flashes was only about ten feet, and Dixon's muscular agility was far superior to that of his antagonists. By constant whirling and dodging he was able to either catch the violet bolts upon his shielded arm or else dodge them entirely. Yet, in spite of the Centaurians' clumsy slowness, they maneuvered with a cool strategy that constantly kept the Earth man's superior strength at bay. Always as Dixon tried to close with one of them he was forced to retreat when a flanking attack from the other threatened his unprotected back. And always the Centaurians maneuvered to bar Dixon from attempting any dash toward the projectile. * * * * *