Between him and the savage beast that had chased him for miles over the swamp stood an old battle-scarred Stegosaurus, fully twenty feet in length, its spines jutting into the air far above the boy’s head. As he looked, the armored tail, with its jagged, horny plates, lashed out at the unicorn and felled it to the ground. The beast half tried to rise and lunged its horn, white in the moonlight, at the throat of its terrible foe. But no weapon could pierce that living fortress of defense and the horn slipped uselessly over the scales. The head of the Stegosaurus—so tiny for so great a bulk of body—bent as though to smell the wounded creature that the blow of his tail had crushed, but, not being an eater of flesh, the huge living fortress turned scornfully away. Injured, but not mortally, the unicorn half rose, when Perry, seizing his chance, drew from his belt his hunting-knife and slit the creature’s throat. Then, placing one foot on the body of the animal, he cried aloud—the faded green book fluttering from his lap as he sprang up— “I’ve caught a unicorn!” CHAPTER III PIRATES OF THE AIR Perry’s father, whose entrance had awakened the boy, looked quizzically at the lad as he stood rubbing the sleep out of his eyes. “I don’t know about catching a unicorn,” the old merchant said, with more than a trace of amused understanding in his tone, “but there’s a big chance that you’ve caught a cold! You’d better get to bed, son, just about as quickly as you know how. Then you can go ahead and catch all the unicorns you want.” The boy looked a little shame-faced at having disclosed the fact that he had fallen asleep and had dreamed of the monsters on which his mind had been set, but his father put his hand on the lad’s shoulder, and said kindly: “We’ll talk about this again some other time, Perry, and if you really feel that you want to take up a fossil-hunter’s life, I’ll not put anything in your way. I had hoped—” he added regretfully, “that you would come right into my business, but after all, every tub must stand on its own bottom. If you do go into the scientific work, I’ll at least have the satisfaction of seeing some of my own old dreams coming true, even though at second-hand. Slip along to bed, now, lad.” Still only half-awake, Perry made some indistinct reply, undressed and in a few minutes was fast asleep, this time too soundly even to dream of monsters, until the light of a morning that had forgotten those ancient times, woke him to the interests of a new day. It did occur to him, though, as he was dressing, that the sun as it rose that morning had risen just the same, thousands of years ago, and would rise the same way hundreds of thousands of years hence, and he wondered what kind of creatures would be living on the earth then.