The little submarine shuddered in every plate and member as monstrous coils encircled her and tightened inexorably in terrific, rippling surges eloquent of mastodonic power; and a strident vibration smote sickeningly upon Terrestrial eardrums as the metal spikes of the monstrosity crunched and ground upon the outer plating of their small vessel. Costigan stood unmoved at the plate, watching intently; hands ready upon the controls. Due to the artificial gravity of the lifeboat it seemed perfectly stationary to its occupants. Only the weird gyrations of the pictures upon the lookout screens showed that the craft was being shaken and thrown about like a rat in the jaws of a terrier; only the gauges revealed that they were almost a mile below the surface of the ocean already, and were still going downward at an appalling rate. Finally Clio could stand no more. "Aren't you going to do something, Conway?" she cried. "Not unless I have to," he replied, composedly. "I don't believe that he can really hurt us, and if I use a ray of any kind I'm afraid that it will kick up enough disturbance to bring Nerado down on us like a hawk after a chicken. However, if he takes us much deeper I'll have to go to work on him. We're getting down pretty close to our limit, and the bottom's a long way down yet." Deeper and deeper the lifeboat was dragged by its dreadful opponent, whose spiked teeth still tore savagely at the tough outer plating of the craft until Costigan reluctantly threw in his power switches. Against the full propellant thrust the monster could draw them no lower, but neither could the lifeboat make any headway toward the surface. The Terrestrial then turned on his rays, but found that they were ineffective. So closely was the creature wrapped around the submarine that his weapons could not be brought to bear upon it without melting the vessel's own outer skin. "What can it possibly be, anyway, and what can we do about it?" Clio asked. "I thought at first it was something like a devilfish, or possibly an overgrown starfish, but it's too flat, and has no body that I can see," Costigan made answer. "It must be a kind of flat worm. That doesn't sound reasonable--the thing must be all of a hundred meters long--but there it is. The only thing left to do now, as I see it, is to try to boil him alive." He closed other circuits, diffusing a terrific beam of pure heat, and the water all about them burst into furious clouds of steam. The boat leaped upward as the metallic fins of the gigantic worm fanned vapor instead of water, but the creature neither released its hold nor ceased its relentlessly grinding attack. Minute after minute went by, but finally the worm dropped limply away--cooked through and through; vanquished only by death.