In spite of that, the 'pedes had won this battle. They had unleashed a new weapon while the defenders had turned to watch the struggle. A rain of vermin seemed to come from the sky. For, thrust deep into the mud outside the fence, were whip-like catapults. Ten animals were drawing back each slingshot, flinging a 'pede into the enclosure! Dismayed, MacAloon watched them hurtle over the wire in unbelievable numbers. Shooting wildly at them, yet fixed to the ground they were defending, the fishmen were desperately near panic. "Stop firing!" Mac shouted. His order was ignored. He cursed and pulled half of the natives away, giving their flame-throwers to the remaining guards. The first half he sent inside the compound with snapped instructions. The others he placed just before the concrete rampart. Armed with two weapons instead of one, each fishmen had double firing power. "Let them reform their ranks inside the camp," Mac ordered. "Then let them have it!" Limpy communicated the command to Swede on the other side of the compound. The haphazard blasts stopped. Undisturbed now, the centaurpedes well into military formation, as Mac had expected. When their lines were twenty deep, they advanced, a black, tight unit with champing mandibles. "Now!" MacAloon roared. A withering wall of flame lashed out, burning down the invaders by the hundreds. But reinforcements kept flying over the blue-flashing fence. And under cover of the air invasion, the pyramids were being built again! The fishmen, backed up against the curved concrete barricade, were unable to reach this new threat with a stream of fire. Obeying his previous instructions, a squad of fishmen came staggering through the doors in the wall. They dragged oxygen and hydrogen tanks that were connected in pairs by flexible, insulated hoses with triggered nozzles. "Forward!" Mac commanded. Limpy passed the word around the besieged mine, and fishmen advanced with blazing flame-throwers. Behind them, the reserves hauled up the tanks. Slowly, stubbornly, the tide of centaurpedes was driven back into the fence. An ear-splitting crackle, and they were gone, a smoking pile of cinders. Even after the camp was clear, Mac did not rest. He drove the reserves to the fence and kept them firing at the enemy beyond. "Not the 'pedes!" he shouted. They looked up, bewildered, wondering why ammunition should be used, if not to burn down the foe. "Melt the catapults!" he ordered. The natives understood at last that the hand-weapons were too feeble to reduce the crude plastic slingshots, but that the tank flame-throwers were not. They blasted out at the catapults. But the centaurpedes were damnably shrewd. In half the time it had taken the fishmen to comprehend, the vermin had begun pulling up their slingshots and retreating out of range. Harrying his forces to get the catapults, Mac glanced aside and swore viciously. In the gaps between his widely spaced crew, more pyramids were forming.