J. B. Lippincott Company for the pictures from Beard's "American Boy's Book of Bugs, Butterflies, and Beetles" on page [229]; McCook's "Natural History of the Agricultural Ant of Texas" on pages [206] and [213].
McClure's Magazine for the pictures on pages [149] and [157].
Scientific American Publishing Company for the picture from "Scientific American Boy at School" on page [227].
Harper and Brothers for the pictures from McCook's "Nature's Craftsmen" on pages [98], [105], [109], [207], and [208].
Strand Magazine for the pictures on pages [165], [182], and [204].
Charles Scribner's Sons for the pictures from Yard's "Top of the Continent" on page [5]; "Country Life Reader" on pages [9], [64], [85], [114], [186], and [241]; Osborn's "Men of the Old Stone Age" on page [33]. Hornaday's "American Natural History" on pages [116], [117], [119], [123], [130], [144], and [225]; Seton's "Life Histories of Northern Animals" on pages [123], [129], [147], and [151].
Henry Holt and Company for the pictures from Beebe's "The Bird, Its Form and Function" on page [167]; Salisbury's "Physiography" on pages [55], [71], and [167].
Carnegie Institution of Washington for the pictures on pages [8] and [69].
University of Nebraska for the picture on page [37].
Columbia University Press for the picture from Wheeler's "Ants and Their Structure" on page [95].