For two days they continued upon their perilous way. Already the cliffs loomed high and forbidding close ahead without sign of break to encourage hope that somewhere they might be scaled. Late in the afternoon the party crossed a small stream of warm water upon the sluggishly moving surface of which floated countless millions of tiny green eggs surrounded by a light scum of the same color, though of a darker shade. Their past experience of Caspak had taught them that they might expect to come upon a stagnant pool of warm water if they followed the stream to its source; but there they were almost certain to find some of Caspak's grotesque, manlike creatures. Already since they had disembarked from the U-33 after its perilous trip through the subterranean channel beneath the barrier cliffs had brought them into the inland sea of Caspak, had they encountered what had appeared to be three distinct types of these creatures. There had been the pure apes--huge, gorillalike beasts--and those who walked, a trifle more erect and had features with just a shade more of the human cast about them. Then there were men like Ahm, whom they had captured and confined at the fort--Ahm, the club-man. "Well-known club-man," Tyler had called him. Ahm and his people had knowledge of a speech. They had a language, in which they were unlike the race just inferior to them, and they walked much more erect and were less hairy: but it was principally the fact that they possessed a spoken language and carried a weapon that differentiated them from the others. All of these peoples had proven belligerent in the extreme. In common with the rest of the fauna of Caprona the first law of nature as they seemed to understand it was to kill--kill--kill. And so it was that Bradley had no desire to follow up the little stream toward the pool near which were sure to be the caves of some savage tribe, but fortune played him an unkind trick, for the pool was much closer than he imagined, its southern end reaching fully a mile south of the point at which they crossed the stream, and so it was that after forcing their way through a tangle of jungle vegetation they came out upon the edge of the pool which they had wished to avoid. Almost simultaneously there appeared south of them a party of naked men armed with clubs and hatchets. Both parties halted as they caught sight of one another. The men from the fort saw before them a hunting party evidently returning to its caves or village laden with meat. They were large men with features closely resembling those of the African Negro though their skins were white. Short hair grew upon a large portion of their limbs and bodies, which still retained a considerable trace of apish progenitors. They were, however, a distinctly higher type than the Bo-lu, or club-men.