The boy came out of his deck-chair with a jump, tripping over his steamer rug and nearly pitching headlong in his hurry. He scrambled to the rail and followed with his glance his uncle’s pointing finger. There, not more than seventy-five feet from the vessel’s side, were the moving and undulating coils of what, at first sight, appeared to be a huge snake. Just for a moment, and then a picture that he had seen flashed back to the boy’s remembrance, and he turned to his uncle with a look of reproach. “Uncle George, that’s only a school of porpoises!” “Fooled you for a minute, didn’t they?” queried his leader. “Yes,” the boy admitted, “they certainly did. But only for a minute.” “Supposing you had never heard of porpoises, that you had seen them just once and that on a misty morning, seen them the way you saw them just now, heaving themselves clear out of the water, one after the other in a long wavering line, don’t you think you might have reported that you had seen the sea-serpent?” “Likely enough,” the lad agreed. “But about the sea-serpent, Uncle George, I’ve often wondered. Do you suppose that there was ever any real reason for the yarn?” “Why do you call it a yarn?” queried the scientist sharply. “Why not?” was Perry’s astonished answer. “There isn’t any sea-serpent, is there?” “You seem pesky sure about it,” his uncle retorted, with a distinct trace of irritation in his manner. “But I thought every one knew it was a fake!” “That what was a fake?” [Illustration: _Courtesy of Pall Mall Magazine._ SEA-SERPENT ATTACKING A PIRATE SHIP. Fanciful sketch, but the red flowing mane may have been suggested by an oarfish, of which specimens fifty feet long have been found.] “The sea-serpent yarn.” “You persist in calling it a ‘yarn,’” his uncle warned him. “Get out of that habit, Perry, it won’t do you any good. It’s never safe to say that a certain thing does not exist, until you have absolute proof that it cannot exist. No one would have expected to find birds with teeth or lizards with wings, yet, as you know, there were plenty of these, and we have found many specimens. As for your way of talking about a sea-serpent ‘yarn,’ don’t forget that millions of sea-serpents swam in the oceans of long ago.” “Could there be an Ichthyosaurus still living in the bottom of the sea?” hazarded the boy. The professor wheeled on him in an instant. “What was an Ichthyosaurus,” he asked sharply, “fish or reptile?” “Reptile,” answered the boy promptly. “Do true reptiles have gills?” The question staggered Perry, for he did not know. He thought for a moment, and then remembered that all water-dwelling reptiles came up to the surface to breathe, so he answered: “I’m not sure, Uncle George, but I don’t think any of them have.” “They haven’t,” was the crisp correction. “How, then, could any of them be living in the bottom of the sea?” The scientist snorted impatiently and paced the deck.