For hours the hard-pressed beast had fled across the Martian desert with its dark rider. Now it was spent. It faltered and broke stride, and when the rider cursed and dug his heels into the scaly sides, the brute only turned its head and hissed at him. It stumbled on a few more paces into the lee of a sandhill, and there it stopped, crouching down in the dust. The man dismounted. The creature's eyes burned like green lamps in the light of the little moons, and he knew that it was no use trying t