"To save us all from the beetles," answered the girl. "When they see us in the shells, they will not know we are human. That is what makes it so hard to have to be eaten by those beetles, when they are such dumb-bells," she added, reproducing another of Tommy's words. "Come," she continued bravely, "let us see if we can pass the fire." * * * * * The roaring fountain made the air a veritable inferno. Overhead the rocks were red-hot. A cascade of sparks tumbled in a fiery shower from the rock roof. Dodd, holding Haidia in his arms, to protect her, staggered ahead, with Tommy in the rear. Only the beetle-shells, which acted as non-conductors of the heat, made that fiery passage possible. There was one moment when it seemed to Tommy as if he must let go, and drop into that raging furnace underneath. He heard Dodd bawling hoarsely in front of him, he nerved himself to a last effort, beating fiercely at his blazing hair--and then the heat was past, and he had dropped unconscious upon a bed of cool earth beside a rushing river. He was vaguely aware of being carried in Dodd's arms, but a long time seemed to have passed before he grew conscious again. He opened his eyes in utter darkness. Dodd was whispering in his ear. "Tommy, old man, how are you feeling now?" Dodd asked. "All--right," Tommy muttered. "How's Haidia?" "Still unconscious, poor girl. We've got to get out of here. I heard Bram yelling in the distance. He's discovered our flight. There may be another way out of the cave, and, if so, he'll stop at nothing to get us. See if you can stand, but keep your head low. There's a low roof of rock above us." "There's water," said Tommy, listening to the roar of a torrent that seemed to be rushing past them. "It's a stream, and I believe these shells will float and bear our weight. We've got to try. We've got to put everything to the touch now, Tommy. I'm going to lay Haidia on one of the shells, poor girl, and start her off. Then I'll follow, and you can bring up the rear." "I'm with you," said Tommy, getting upon his feet, and uttering an exclamation of pain as, forgetful of Dodd's injunction, he let his head strike the rock roof overhead. * * * * * In the darkness he felt the outlines of his beetle-shell lying beside the torrent. He could hear Dodd in front of him, grunting as he raised Haidia's unconscious form in his arms and deposited her in her shell. Tommy got his own shell into the stream, and held it there as the waters swirled around it. "Ready?" he heard Dodd call. Before he could answer, there sounded from not far away, yet strangely muffled by the rocks, Bram's bellow of fury. Bram was evidently fully drugged and beside himself. Inarticulate threats came floating through the rocky chamber. "Bram seems to have lost his head temporarily," called Dodd, laughing. "A madman, Tommy. He insists that the marsupial lion--"