It was not love of adventure alone or interest in the strange new forest growths that had drawn Ken to the jungle. His uncle, the one who had gotten Ken letters from the Forestry Department at Washington, had been proud of Ken’s Arizona achievements. This uncle was a member of the American Geographical Society and a fellow of the New York Museum of Natural History. He wanted Ken to try his hand at field work in the jungle of Mexico, and if that was successful, then to explore the ruined cities of wild Yucatan. If Ken made good as an explorer his reward was to be a trip to Equatorial Africa after big game. And of course that trip meant opportunity to see England and France, and, what meant more to Ken, a chance to see the great forests of Germany, where forestry had been carried on for three hundred years. In spite of the fact that the inducement was irresistible, and that Ken’s father was as proud and eager as Ken’s uncle to have him make a name for himself, and that Hal would be allowed to go with him, Ken had hesitated. There was the responsibility for Hal and the absolute certainty that Hal could not keep out of mischief. Still Ken simply could not have gone to Mexico leaving his brother at home broken-hearted. At last the thing had been decided. It was Hal’s ambition to be a naturalist and to collect specimens, and the uncle had held out possible recognition from the Smithsonian Institution at Washington. Perhaps he might find a new variety of some animal to which the scientists would attach his name. Then the lad was passionately eager to see Ken win that trip to Africa. There had been much study of maps and books of travel, science, and natural history. There had been the most careful instruction and equipment for semi-tropical camp life. The uncle had given Ken valuable lessons in map-drawing, in estimating distance and topography, and he had indicated any one of several rivers in the jungle belt of Mexico. Traversing one hundred miles of unknown jungle river, with intelligent observation and accurate reports, would win the prize for Ken Ward. Now the race was on. Would Ken win? Presently the train crossed a bridge. Ken Ward had a brief glance at clear green water, at great cypress-trees, gray and graceful with long, silvery, waving moss, and at the tangled, colorful banks. A water-fowl black as coal, with white-crested wings, skimmed the water in swift wild flight, to disappear up the shady river-lane. Then the train clattered on, and, a mile or more beyond the bridge, stopped at a station called Valles. In the distance could be seen the thatched palm-leaf huts and red-tiled roofs of a hamlet.