There was a sudden movement behind a close ridge. Momentarily John Hall was rendered paralyzed. Then he backed slowly toward the ship and safety behind a Johnson heat ray. The vague form abruptly materialized, etched in black against the twilight horizon of Ganymede. The effect was startling. The creature stood upright, on two legs, with two gnarled, lengthy arms dangling from its bony shoulders. Human? The question registered itself on his brain, and the thing in front of him gave unwitting reply, as it moved to a clearer position. No, not human. Maybe not even animal. Two great eyes bulged curiously from a drawn, shrunken, monkey-like face. The body was as warped and distorted as the bole of an old oak tree. With pipe-stem arms and legs, bulging at the joints. Its most natural position seemed to be a crouch, with the arms dragging on the ground. Somehow this travesty of human form struck him as being humorous. He chuckled throatily, and then stopped with a start as the same chuckle crudely vibrated back, echo-like. But it was no echo! No, that wasn't possible. John raised his hand to scratch his head through force of habit; forgetful that this was impossible through the thick glassite helmet he wore. The tall, gangling creature in front of him watched closely for a moment, then stretched one preposterously long limb up and scratched briskly on his leathery skull in imitation of John Hall. The answer struck him instantly. Why hadn't he thought of it. This animal, this thing, whatever it was, was a natural mimic. Such a thing was not unknown on earth. Monkeys often imitated the gestures of humans. Parrots prattled back powerful expletives and phrases. He rather welcomed his new find now. It would be pretty dismal all alone on desolate Ganymede with no one to talk to but himself, and this strange animal would undoubtedly help to lighten the long, dreary hours, perhaps days, that stretched ahead of him until rescue came. Certainly there was nothing to fear from this creature; not at least by himself, born to resist the pull of a gravity force many times more powerful then that of Ganymede's. * * * * * He walked slowly toward the creature viewing its reactions carefully. It held its ground. Evidently fear was not an element in its makeup. Why should it be? Doubtlessly these things were the only animate life on the globe. Masters of all they surveyed. No other beings to contest their supremecy. No need then for fear or even for savageness. They were, undoubtedly, happy-go-lucky beasts who scavenged the bleak, rocky surface of the moon for hardy mosses or whatever they lived on. He heard a scuffing noise to his left. Another creature, similar almost in every detail to the first had popped into view. That seemed to be a signal for a dozen others to haphazardly appear from the most unexpected places and niches. One rose up within a few feet of Hall and blinked its great eyes at him in greeting.