The plates illustrating the dissections have all been drawn originally for the book from actual dissections. Most of the other figures are original, either drawn or photographed directly from nature, or from preserved specimens. Credit is given in each case for figures not original. The drawings for all of the figures of dissections and for all original figures not otherwise accredited were made by Miss Mary H. Wellman, to whom the author expresses his obligations. The thanks of the author are due to Mr. George Otis Mitchell, San Francisco, who kindly made the photo-micrographs of insect structure from the author's slides; to Professor Mark V. Slingerland, Cornell University, for electros of his photographs of insects; to Dr. L. O. Howard, U. S. Entomologist, for electros of figs. 45, 52, 56, 68, 81, 82, 83, 84, 87, 90, and 92; to Professor L. L. Dyche, University of Kansas, for photographs of his mounted groups of mammals; to Mrs. Elizabeth Grinnell, Pasadena, Calif., for photographs of birds; to Mr. J. O. Snyder, Stanford University, for photographs of snakes; to Mr. Frank Chapman, editor of "Bird-lore," for electros of photographs of birds; to Mr. G. O. Shields, editor of "Recreation," for an electro of the photograph of a bird; to the American Society of Civil Engineers for electros of photographs of boring marine worms; to Cassell & Co., for electros of three photographs from nature; to Geo. A. Clark, secretary Fur Seal Commission for photographs of seals; and to the Whitaker and Ray Co., San Francisco, for electros of figs. 46, 59, 60, 61, 64, 65, 93, 94, 97, 98, 99, 100, 102, 119, and 166 to 172, published originally in Jenkins & Kellogg's "Lessons in Nature Study." The origin of each of these pictures is specifically indicated in connection with its use in the book. The author's sincere thanks are also due to Mrs. David Starr Jordan and to Mr. J. C. Brown, graduate student in zoology in Stanford University, for their assistance in the correction of the MS., and in the preparation of the laboratory exercises respectively. The chapters of Part II relating to the vertebrates were read in MS. by President David Starr Jordan, whose aid and courtesy are gratefully acknowledged. Similar acknowledgments are due Professors Harold Heath and R. E. Snodgrass for reading the proofs of the directions for the laboratory exercises. VERNON LYMAN KELLOGG. STANFORD UNIVERSITY, May, 1901. FOOTNOTES: