Introduction
Zoology is that branch of Natural History which treats of animals, and embraces not only their structure and functions, their habits, instincts, and utility, but their names and systematic arrangement.
Various systems have been proposed by different naturalists for the scientific arrangement of the animal kingdom, but that of Cuvier, with some modifications, is now thought the best, and a sketch of it will be found under the head of the Modern System in this Introduction. As, however, the System of Linnæus was formerly in general use, and is still often referred to, it has been thought advisable to give a sketch of it first; that the reader may be aware of the difference between the old system and the new one.