Sure enough, he had secured his prize, and then he pointed to another, which Fred immediately captured. Then the Doctor explained that they had found the famous Leaf Butterfly of Borneo, that has the peculiarity of resembling almost to perfection a dead leaf of the tree he inhabits. "You observe," said he, "that his two sets of wings have a dark line running along them from point to point that exactly resembles the midrib of a leaf, and there are lines running out from this centre that correspond to its veins. When the wings are folded, the lower end of them imitates the stem, and touches the twig when the butterfly is at rest; and their upper extremity is pointed in exact imitation of the point of the leaf. It is the habit of this butterfly to settle where there are several dead or partly withered leaves, and you must have very sharp eyes to distinguish him from one of them." While the Doctor was talking the boys observed that their specimens were not exactly alike, and they called his attention to their discovery. The latter explained that it was difficult to find an exact resemblance in a dozen or more specimens, and they appeared to vary about as the leaves themselves were varied. It was a provision of nature for the protection and preservation of the butterfly, as he was enabled to escape many of his enemies by adapting his appearance to his retreat. "I suppose," said one of the boys, "it is on the same principle that rabbits in our own country are brown in summer and white in winter. Many a bunny has saved himself from the hunters by changing from brown to white when the snow falls." The two butterflies were carefully preserved along with those already captured, and as soon as the men were rested the boat moved on. Suddenly one of the Dyaks called out, "Mias! mias!" and pointed to the top of a tree where there was an animal of considerable size swinging from one limb to another, and apparently enjoying himself. Our friends looked, and the boys hardly needed the Doctor's explanation that "mias" is the Malay name of the famous orang-outang. "What a splendid fellow he is," said Frank, "and what a pity we cannot capture him! He looks as though he was six feet high at least." "The gentleman we met as we went down the coast of Sumatra told us that none had ever been caught more than four feet and two inches high," responded Fred, "but this one certainly appears as large as a full-grown man." "Probably a measurement would tell a different story," Doctor Bronson remarked. "You know," he added, "that the largest fishes are the ones that are not caught, or get no farther than being hooked and lost."