---Transcriber's Note:
- Minor typographical errors have been corrected without note.
- Punctuation and spelling were made consistent when a predominant form was
found in this book; otherwise they were not changed.
- Ambiguous hyphens at the ends of lines were retained.
- Mid-paragraph illustrations have been moved between paragraphs
and some illustrations have been moved closer to the text that
references them.
- "... the shells of the eggs in class Aves."* (Page 152.) A footnote is
indicated but missing from the text.
- The Contents table was added by the transcriber.