At the word the animal sprang off, and commenced quartering the ground for a couple of hundred yards in advance. Following him, the horseman moved forward. In this way he approached the point where the two walls converging narrowed the canon to a space of little more than a hundred yards. Along the bases of the cliffs, on both sides, lay large loose rocks, that would have given cover to men in ambush, and even horses might have been concealed behind them. "This," thought Carlos, "would be the place chosen for their cowardly attack. They might hit me from either side with half an aim. But Cibolo makes no sign.--Ha!" The last exclamation was uttered in a short sharp tone. It had been called forth by a low yelp from the dog. The animal had struck the trail where the yellow hunter and his companion had crossed to the middle of the ravine. The moon had again emerged from the clouds, and Carlos could see the dog dashing swiftly along the pebbles and up the ravine towards the mouth of the cavern! His master would have called him back, for he was leaving the loose rocks unsearched, and, without that being done, Carlos felt that it would be perilous to proceed farther; but the swiftness with which the dog had gone forward showed that he was on a fresh trail; and it now occurred to the cibolero that his enemies might be within the cave itself! The thought had hardly crossed his mind when the dog uttered several successive yelps! Although he had got out of sight, his master knew that he was at that moment approaching the mouth of the cave, and running upon a fresh scent. Carlos drew up his horse and listened. He dare proceed no farther. He dared not recall the dog. His voice would have been heard if any one were near. He reflected that he could do no better than wait till the dog should return, or by his attack give some sign of what he was after. It might, after all, be the grizzly bear, or some other animal, he was pursuing. The cibolero sat upon his horse in perfect silence--not unprepared though for any sudden attack. His true rifle lay across his thighs, and he had already looked to its flint and priming. He listened to every sound, while his eyes pierced the dark recesses of the ravine before and around him. For only a few moments this uncertainty lasted, and then back down the chasm came a noise that caused the listener to start in his saddle. It resembled the worrying of dogs, and for a moment Carlos fancied that Cibolo had made his attack upon a bear! Only a moment did this illusion last, for his quick ear soon detected the voices of more dogs than one; and in the fierce confusion he distinguished the deep-toned bark of a _bloodhound_! The whole situation became clear to him at once. His enemies had been awaiting him in the cave--for from it he was certain that the sounds proceeded. His first instinct was to wheel his horse and gallop out of the canon. He waited a moment, however, and listened.