It would not have been fair to ask Ken just then whether the prize for which he worked was worth his present gain. _Garrapatoes_ may not seem important to one who simply reads about them, but such pests are a formidable feature of tropical life. However, Ken presently felt that he was himself again. Then he put his mind to the serious problem of his note-book and the plotting of the island. As far as his trip was concerned, Cypress Island was an important point. When he had completed his map down to the island, he went on to his notes. He believed that what he had found out from his knowledge of forestry was really worth something. He had seen a gradual increase in the size and number of trees as he had proceeded down the river, a difference in the density and color of the jungle, a flattening-out of the mountain range, and a gradual change from rocky to clayey soil. And on the whole his note-book began to assume such a character that he was beginning to feel willing to submit it to his uncle. *XVI* *FIELD WORK OF A NATURALIST* That night Ken talked natural history to the boys and read extracts from a small copy of Sclater he had brought with him. They were all particularly interested in the cat tribe. The fore feet of all cats have five toes, the hind feet only four. Their claws are curved and sharp, and, except in case of one species of leopard, can be retracted in their sheaths. The claws of the great cat species are kept sharp by pulling them down through bark of trees. All cats walk on their toes. And the stealthy walk is due to hairy pads or cushions. The claws of a cat do not show in its track as do those of a dog. The tongues of all cats are furnished with large papillæ. They are like files, and the use is to lick bones and clean their fur. Their long whiskers are delicate organs of perception to aid them in finding their way on their night quests. The eyes of all cats are large and full, and can be altered by contraction or expansion of iris, according to the amount of light they receive. The usual color is gray or tawny with dark spots or stripes. The uniform tawny color of the lion and the panther is perhaps an acquired color, probably from the habit of these animals of living in desert countries. It is likely that in primitive times cats were all spotted or striped. Naturally the boys were most interested in the jaguar, which is the largest of the cat tribe in the New World. The jaguar ranges from northern Mexico to northern Patagonia. Its spots are larger than those of the leopard. Their ground color is a rich tan or yellow, sometimes almost gold. Large specimens have been known nearly seven feet from nose to end of tail.