With three exceptions these chapters have appeared in the pages of The Atlantic Monthly, and I publish them through the kindness of the Editor, Ellery Sedgwick. "Hoatzins at Home" is adapted from a title in my Tropical Wild Life, Volume I, published by the New York ZoÖlogical Society, which deals with the more technical results of study at the Research Station. The illustrations are from my own photographs, except the frontispiece and those facing pages 162, 186, and 268, which were taken by Paul G. Howes. All the chapters dealing with the jungle relate to Bartica District, British Guiana, except X, which refers to ParÁ at the mouth of the Amazon.