There is no other book just like this. Not only does it give the salient facts of structural zoÖlogy and the development of the various branches of animals, but also the natural history—the life and habits—thus showing the interrelations of structure, habit, and environment. In a word, it gives the principles of zoÖlogy and their actual application. The economic phase is emphasized.

Part I—the Field and Laboratory Guide—is designed for practical instruction in the field and laboratory. To enhance its value for this purpose blank pages are inserted for notes.