Its head was long and rectangular, and much too large for its body, judged by the make-up of earthly flying creatures. Its skin was cold and scaly like that of a lizard. Its wings were bat-like, except that the skin was stretched on a single long finger, instead of on four. The other fingers were short and free, and equipped with sharp claws. The back of the wing, along the arm part, was covered with long feathery scales. The tail was as out of proportion as the head, and sported a fan of scales at its tip. The smell was nauseatingly like that of a snake. It was evident that he held in his hand a small variety of pterodactyl, apparently similar in every respect to the reptilian forerunners of birds on our own planet. But its companions were becoming altogether too numerous and troublesome to leave him any leisure for further scientific investigation of his captive. So, casting it from him, he set about defending himself. A perfect swarm of the filthy little creatures now encompassed him in the pitch darkness of the cave. They battered against him, and tore at his naked body with their sharp claws and teeth. More and more of them kept arriving, so that it soon became evident that he must escape from them in some way and in some haste, in order to avoid being overpowered. So, warding them off as best he could with one hand, he turned sharp to the right and groped his way around the wall of the grotto with his other hand. Finally he came to an opening, which he entered at once. Of course it might be that he had completely circumnavigated the cave, and that this was the same tunnel through which he had entered. Even so, it would be better to return to the ledge and the river, than to be overwhelmed by this rapidly augmenting swarm of pterodactyls. But no, it was not the same tunnel, for it did not grow smaller as he progressed; so, after frantically beating at the bat-like creatures with both hands for a moment, he crossed his arms Boy Scout fashion in front of his face and fled precipitately down the corridor. This way proved to be practically straight. His outstretched hands prevented any collision with the walls or other obstacles, which otherwise must inevitably have occurred in the pitch darkness. Cabot was not quite as helpless in the dark as most earth men would have been, for he had over three years of experience with the inky, starless Porovian nights. As he ran on, his tormentors gradually dropped behind him, until finally they were reduced to only two or three more determined members of the breed. Cabot accordingly slowed down to a walk. But, just as he did so, one of his feet stepped out into nothingness. With a despairing effort he strove to throw his body backward to safety. He reached out his hands to the sides and then above, groping madly for some support. But all in vain; for, after toppling for it seemed ages on the brink, he pitched over headlong into space—