All images were obtained from The Internet Archive. A link to a clearer version of the illustration of Hylonomus Lyelli (facing [p. 257]) was obtained from Plate 9, The Coal Measures Amphibia of North America, by Roy Lee Moodie. Illustrations were repositioned so as to not split paragraphs. Hyphenation was standardized to the most prevalent form and several presumed typos were corrected.