At last he came to Unicorns. Page after page of unicorns! The boy read the story of Vertomannus who measured two unicorns that had been presented to the Sultan of Mecca in 1503. He learned how Father Lobo, a missionary, had chased a unicorn in Abyssinia in 1622. He saw the drawings of one-horned asses in China sent to Rome by Grueber, the Jesuit Father, in 1661. From utter disbelief, he passed to doubt, and his doubt received a sudden shock when he read that the Russian naturalist Prjevalsky, in his book “Mongolia,” published in 1876, had declared that the orongo, in northern Thibet, sometimes, though rarely, has one horn, though not in the center of the forehead. To this picture there was a note, in his father’s handwriting, evidently made after he was grown up. It read: “Personally, I see no reason to deny the existence of the unicorn. It is quite likely that occasional specimens of a two-horned animal should only have one horn. The narwhal often has two tusks, but generally only one. If the one-tusked narwhal is a natural development, why not a one-horned antelope? The Nepalese unicorn sheep has one horn, and a rhinoceros, as well.” The faded green book dropped into Perry’s lap, as he leaned back in his chair, thinking. He recalled the finding of the okapi, only a few years before, and his mind pictured an adventurous trip into Central Thibet where the one-horned orongo of Prjevalsky, the unicorn, might still be found. Deeper and more profound grew the day-dream, more and more real the vision, until, with a start, the boy found himself riding at full speed over a coarse-ferned swampy plain. [Illustration: THE UNICORN IN CHINA. The Sz, or Malayan Rhinoceros, as pictured by a Chinese artist in the ’Rh Ya. The Indian Rhinoceros is one-horned. The African square-lipped rhinoceros, or “white rhino,” though possessing two horns, one behind the other, has the forward horn so long and powerful as to be truly unicorn-like, though it is nasal and not frontal.] A warm and steaming mist hung with a dull purple haze over a landscape that seemed familiar, though the boy knew that his eyes had never seen it before. Huge monkey-puzzles thrust their spiny arms into the heavy air, ferns a hundred feet high swayed their livid green tracery against the lowering sky, and here and there a leafless pillar twenty feet in height showed where still remained a struggling horsetail of the weird forests of the age before. Over all hung the red ball of the sun, unable to pierce the low-hung curling wreaths of mist which held the landscape like a bowl. The glow of the half-obscured sun shone dully on the quaking bog and deepened the shadows of huge black forms, monstrous and menacing, which seemed to be sprawling in the ebon water. To these, there was no shape, although their gross inertness breathed of life. In the distance there was a stir, and Perry, gripping his knees hard upon the Thing he rode, cried aloud in the somber stillness— “What moved!”