Down, down--ever more slowly the great disk was sinking, now, down until at last it hovered motionless a scant fifty feet above the surface of the molten lake, hanging level with the edges of the circular stone basin which held that lake, and level with the floor of the mighty cavern. A moment only it hovered there, and in that moment Rowan saw that awaiting it at the great basin's edge stood a half-score of the lizard-men. Even in the moment he saw them they glimpsed him crouching at the disk's edge, and instantly two of them leapt upon the disk, with the white globes that held the heat-beam outstretched toward him. He cowered back, but instead of loosing the ray upon him one grasped him by the shoulder and jerked him from the platform onto the basin's edge, just as the great disk began to move upward from that edge. Standing there for the moment Rowan saw the great disk floating smoothly up once more into the lurid light toward the black round opening of the shaft in the roof of rock above, rising swiftly into that shaft and disappearing from view inside it as it flashed upward once more on its endless, automatic motion. As one of his captors tugged suddenly at his arm, though, he turned, and the creature pointed toward the gigantic gray buildings ahead, at the same time jerking him forward. Slowly Rowan started toward them, while on each side of him walked one of the lizard-men, their deadly white globes ready for action. A moment and they had left the broad clear plaza of stone where lay the fiery lake, and were entering one of the wide streets which cut across the masses of the city's buildings. As he marched down that street between his two guards Rowan all but forgot his own predicament, so intensely interesting was the panorama before his eyes, a shifting pageant of creatures of the world's youth, enthralling to the eyes of the paleontologist. For through the streets were pouring masses of the lizard-men, bearing tools or weapons, hurrying along on taloned feet or riding huge brontosaurs, who tramped majestically along the street's center while the walking crowds clung to its sides. Here and there, too, moved other dinosaurs, almost as huge, bearing burdens or ridden by lizard-men, the reptilian beast-servants of a lizard race. Tyrannosaurs there were, moving along in their swift, hopping gait, the fiercest and most terrible of all the dinosaurs, yet servants, like the rest, of the green-scaled lizard-folk; allosaurs, like smaller replicas of the great tyrannosaurs; mighty-armored stegosaurs and great-horned triceratops, and over all the whirring wings of the great pterodactyls.