Indeed he was not afforded the opportunity; for he had scarcely reached the broad slope of rock leading up to the circular tunnel which he had been so anxious to explore, when the surface of the pool again became violently agitated, and the monstrous head again appeared, followed this time by an enormous body, four thick, clumsy legs, and a tail; and with a ponderous rush the creature at once made for the spot where Stukely stood. But Phil, without waiting for further developments, incontinently turned tail, and, stooping, bolted up the tunnel-like opening, the comforting assurance coming to him that so monstrous a beast could not possibly enter so comparatively small a passage. Moreover, he was right, for after running a few feet he looked back over his shoulder and saw that although the beast had thrust its head, as far as its eyes, into the opening, it could advance no farther. Then, summoning all his courage to his aid, he retraced his steps, and, plucking an arrow from his quiver, poised it in his hand for a moment-- he could not use his bow, as it was too long to be drawn in so confined a space--and then hurled it with all his strength straight at the beast's left eye. The missile flew true--indeed it could scarcely miss at such exceedingly short range--and buried itself half its length in the great blinking orb; whereupon, with a bellowing roar that echoed and reverberated like thunder in that underground chamber, the monstrous head was suddenly withdrawn, and the next moment a sound of tremendous splashing told the hardy assailant that his enemy had precipitately retreated to the depths of the pool. Then, acting more by instinct than reason, Phil rushed back along the way which he had come, out of the tunnel, on to and along the ledge--heedless of the violent disturbance of the water which told of the convulsive movements of the enormous shape hidden beneath its surface--and so back to the cavern entrance, out of which he rushed almost as precipitately as the ape had done half an hour earlier. "No wonder," thought the young man, "that the poor beast was frightened, if he happened to catch a glimpse of the monster of the pool!" Some two hours later he turned up at the spot where the little party had made their temporary camp beside the river, and nonchalantly flung to the ground the carcass of a Guazu-puti deer which he had chanced to encounter on his way back. He found that Dick and Vilcamapata had made good use of their time during his absence, for they had not only found a splendid tree out of which to fashion a canoe, but had actually felled it; and there it lay, within a couple of hundred feet of the river, ready to be hewn into shape and hollowed out. "You've been away a long time," remarked Dick; "gramfer here and I were seriously discussing the desirability of starting out to look for you. Have you found the game scarce?"