[Illustration: _The expoder hammered in Rolf's heavy fist._] Tanner smashed an elbow into Rolf's side. "Retreat!" he gasped. The Furry Amazons swarmed up over the lower terraces of rocks, their snaky heads thrust forward and their swords slashing. The two Earthmen bounded up and backward to the next jumbled layer of giant blocks behind them, their powerful earthly muscles negating Lomihi's feeble gravity. Spears showered thick about them and then they dropped behind the sheltering bulk of a rough square boulder. "Now where?" Rolf snapped another burst of expoder needles at the furry attackers as he asked. "To the vaults beneath the Forbidden City," Mark Tanner cried. "None but the Outcasts and we two have entered the streets of deserted Aryk." The bald scientist slung his bow over his head and one shoulder and went bounding away along a shadowy crevice that plunged raggedly into the heart of the Barrier. Rolf blasted another spurt of explosive needles at the Furry Ones and followed. * * * * * Darkness thickened as they penetrated into the maze of the Barrier's shattered heart. An unseen furry shape sprang upon Rolf's shoulders and as he sank to his knees he felt hot saliva drip like acid upon his neck. His fist sent the attacker's bulk smashing against the rocky floor before fangs or claws could rip at his tender flesh, and he heard a choked snarl that ended convulsively in silence. Bat-winged blobs of life dragged wet leathery hide across his face, and beneath his feet slimy wriggling things crushed into quivering pulp. Then there was faint light again, and the high-vaulted roof of a rock dungeon rose above him. Mark Tanner was peering out a slitted embrasure that overlooked the desolate land of the Hairy People. Tanner's finger pointed. "Altha!" Rolf saw the graceful wings of the glider riding the thermals back toward the Barrier. "She had warned the Hairy People, and now she returns." "The weasel heads won't follow us here?" asked Rolf. Tanner laughed. "Hardly. They fear the spirits of the Ancients too much for that. They believe the invisible powers will drink their souls." "Then how about telling me about this hanging world?" "Simply the whim of an ancient Martian ruler. As I have learned from the inscriptions and metal tablets here in Aryk he could not conquer all of Mars so he created a world that would be all his own." Rolf laughed. "Like the pleasure globes of the wealthy on Earth." "Right." Tanner kept his eyes on the enlarging winged shape of Altha's flyer as he spoke. "Later, when the nations of Mars began draining off the seas and hoarding them in their underground caverns, Lomihi became a fortress for the few thousand aristocrats and slaves who escaped the surface wars.