This textbook provides the foundation for a course in zoology. Popular names have been employed as far as possible, but the technical terms have been added in brackets. The design of this work is to furnish an epitome of the leading principles of the science of zoology, as deduced from the present state of knowledge, so illustrated as to be intelligible to the beginner. No similar treatise now exists in this country, and, indeed, some of the topics have not been touched upon in the English language, unless in a strictly technical form, and in scattered articles. Being intended for American students, the illustrations have been drawn, as far as possible, from American objects: some of them are presented merely as ideal outlines, which convey a more definite idea than accurate sketches from nature; others have been left imperfect, except as to the parts especially in question; a large proportion of them, however, are accurate portraits from original drawings. The first part is devoted to comparative anatomy, physiology, and embryology, as the basis of classification, and also to the illustration of the geographical distribution and the geological succession of animals; the second to systematic zoology, in which the principles of classification are applied, and the principal groups of animals are briefly characterized.