“Work yourself out! I did!” yelled Dick. “Can’t fire! Got no revolver! I won’t desert you, though! I’ll follow on!” The Plesiosaurus had now disappeared down the trail. It went sliding down over the slippery rocks, and now the boys were able to understand what made it so smooth. Probably this had been the monster’s path for years. “Oh, it’s terrible! Terrible!” cried Clara. “Oh, Dick! Can nothing be done to save that man?” “There’s his rifle now, standing against the hut!” cried Charley. “Why didn’t we think of it before?” Dick made a rush for the rifle, and sprang to the head of the trail. “It will do no good, anyhow, but here goes!” he cried. He fired, but with no result, just as he had anticipated. The bullet struck the monster on its scaly back and glanced off as if it had been fired against boiler plate. Down the steep slope the Plesiosaurus went sliding. Dr. Dan’s cries grew fainter. All gave the faithful guide up for lost. “It’s no use!” groaned Dick. “I must go after him, though. I said I would, and so I will!” “Oh, Dick, don’t go! Don’t go!” pleaded Clara. “For gracious sake don’t try it!” shouted Charley. “It’s all your life is worth, Dick!” But Dick had already started, and there was no such thing as holding him back. And yet if he had only known it, there was a safe and easy way down over those cliffs not ten yards distant from the hut. But the way Dick had taken was not only very difficult, but highly dangerous. It was frightfully steep, too, with scarce a foothold, and as smooth as glass. Down this terrible incline the Plesiosaurus slid easily enough, and no doubt it had come up the same way many times, its queer webbed feet acting as suckers like the feet of a fly. But Dick possessed no such power. He could only crouch down “on his hunkies,” as the boys say, and go sliding along after old P. D. What if he should overtake the monster and run into him? he could not help thinking; but there was no such danger, for old P. D. went faster than he could go by far, and yet to Dick it seemed as though he was sliding down with lightning speed. When he reached the level ridge below he struck it with such force that he went over on his face, hitting his head and knocking the wits out of him for the moment. The next he knew he was scrambling up trying to save himself from slipping over the edge of another precipice, the ground slipping away under his feet. Dick drew back in horror just in time to save himself. Springing aside on the firmer ground, he found himself looking down into a deep, narrow valley inclosed on all sides. There was a lake at the bottom of this valley, and Dick saw old P. D. in the act of slipping into it. The monster threw up its head as the big body sank beneath the water, and gave one parting bellow, and after that Dick saw him no more, nor did he think of him, for there lying upon the ground at no great distance away was Dr. Dan. Dick ran to the guide and tried to raise him up.