There were twenty of the creatures in this group, and more joined them along the way. They imitated the brisk step of the soldiers with amazing exactness, though they possessed no semblance whatsoever of feet. They moved on dense mats of stubby, resilient bristles that grew from the flat bottoms of their column-bodies, sweeping forward like a horde of self-propelling brooms. Not wishing to be outdone by the visitors, they had their own sergeant, who moved along importantly at the side of his command, glaring threateningly from the corner of his single, huge eye. As Sergeant Hallihan called out his impeccable, "Hut! Twuh, hree, foar," Sergeant B.D. responded with, "Ungh! Ungh, ungh, ungh," the only sound he was capable of uttering. Hallihan scowled over his shoulder and snorted disgruntledly, fervently wishing he could get his heckler alone for a moment. His hard cot would have a new fur mattress that night. Hallihan estimated they were half-way to the mine now. That huge deposit of _chroidex_ salts was important to the system. Without the precious mineral spaceflight would be impossible, since there would be nothing to protect travelers from deadly solar rays. The small amounts that had been found on Earth and the other major planets would soon give out, and Titan was the only other known source of _chroidex_. This deposit would last for centuries, and by the time it, too, was exhausted, perhaps engineers would have figured a way around the difficulty. Captain Staley's car came to a stop and the tall man stepped out. He stood a moment, surveying the weary marchers with sharp, experienced eyes. He knew just how much he could get out of a man, knew when the limits of the human machine had been reached. "You may rest your troops, Sergeant Hallihan," he said shortly. * * * * * Hallihan sighed inwardly, hoping for at least a twenty-minute surcease. He went through the formality of placing his men at ease, then strode anxiously to the captain's side. "Do you suppose there will be trouble with the Squeakers, Sir?" he asked apprehensively. "They don't take to us, you know. They might ambush us at the mine." The Captain thought a moment, then his thin lips drew up in a smile. "I don't think they will. Their crude weapons wouldn't stand a chance against us, in force. Personally, I wish they would attack. Then we could do away with them once and for all. As it is, we can't risk bringing laborers here to develop the mine. After the Squeakers picked off a few of them, the miners would turn tail and run for home. So we're temporarily stuck with both jobs, Sergeant; working the mine, and eliminating the Squeakers. We'll catch the whole damn bunch of them in the open some day. When we do...." The two men momentarily forgot their conversation and turned to watch the antics of the perplexed B.D.s. The shaggy creatures were milling about uncertainly.