Thick about them and far above them towered the masses of strange trees and plant life through which they made their way. Randall could see but dimly the nature of these plant-forms, but could make out that they were grotesque and unearthly in appearance, all leafless, and with masses of thin tendrils branching from them instead of leaves. He realized that it was only beside the arid planet's great canals that this profusion of plant life had sufficient moisture for existence, and that it was the broad bands of jungle bordering the canals that had made the latter visible to earth's astronomers. * * * * * Lanier and he halted for a moment to listen. The thick jungle about them seemed quite silent. But from behind there came through it a vague tumult of hissing calls; and then, as they glimpsed red flashes far behind, they heard the crashing of great masses of the leafless trees. "The rays!" whispered Lanier. "They're beating through the jungle with them and the centipede-machines after us!" They paused no more, but pushed on through the thick growths with renewed urgency. Now and then, as they passed through small clearings, Randall glimpsed overhead the fast-moving nearer moon and slower sailing farther moon of Mars, moving across the steady stars. In some of these clearings they saw, too, strange great openings burrowed in the ground as though by some strange animal. The crashing clamor of the Martians beating the jungle behind was coming close, ever closer, and as they came to still another misty-lit clearing, Lanier paused, with face white and tense. "They're closing in on us!" he said. "They're hunting us down by beating the jungle with those centipede-machines, and even if we escape them we're getting farther from the city and the matter-station each moment!" Randall's eyes roved desperately around the clearing; and then, as they fell on a group of the great burrowed openings that seemed present everywhere about them, he uttered an exclamation. "These holes! We can hide in one until they've passed over us, and then steal back to the city!" Lanier's eyes lit. "It's a chance!" * * * * * They sprang toward the openings. They were each of some four feet diameter, extending indefinitely downward as though the mouths of tunnels. In a moment Randall was lowering himself into one, Lanier after him. The tunnel in which they were, they found, curved to one side a few feet below the surface. They crawled down this curve until they were out of sight of the opening above. They crouched silent, then, listening. There came down to them the dull, distant clamor of the centipede-machines crashing through the jungle, cutting a way with rays, their clamor growing ever louder. Then Randall, who was lowest in the tunnel, turned suddenly as there came to him a strange rustling sound from _beneath_ him. It was as though some crawling or creeping thing was moving in the tunnel below them!