Chapter Third is headed, "Notice of the principal systems of Zoology." It is divided into the six following sections: General remarks upon modern systems; Early attempts to classify animals; Period of Linnaeus; Period of Cuvier, and Anatomical systems; Physiophilosophical systems; Embryological systems.
This chapter is invaluable to the general student, as giving him in a single view not only a _conspectus_, of the most important attempts at classification in Zoology, but an examination of the principles involved in each, by the one among all living men most fitted to perform the task. No cultivated person who desires to know anything of Natural Science can pass over this portion of the work without careful study. Those who are not prepared to follow the author through the details of the Second Part will yet consider these volumes as indispensable companions for reference, as containing this brief but comprehensive encyclopedia and commentary, covering the whole philosophical machinery of zoological science.
For the first section of this chapter Mr. Agassiz adopts the fundamental divisions (branches) of Cuvier, introducing such changes among the classes and orders as the progress of science demands. The second section gives a short account of the early attempts to classify animals, more particularly of the divisions established by Aristotle. The third section embraces the period of Linnaeus, and gives his classification. The fourth, that of Cuvier, and Anatomical systems, with the classifications of Cuvier, Lamark, De Blainville, Ehrenberg, Burmeister, Owen, Milne-Edwards, Von Siebold and Stannius, Leuckart. The fifth section includes the Physiophilosophical systems, with diagrams of Oken's and Fitzinger's classifications, and a special article for the circular groups of McLeay. The sixth and last section is devoted to Embryological systems, and presents diagrams of the classifications of Von Baer, Van Beneden, Kölliker, and Vogt.
The second part of the Monograph introduces us to the consideration of a special subject of Natural History,--the North American Testudinata. Its three chapters treat successively of this order of Reptiles,--of its families,--of its North American genera and species.