I have been called upon to write illustrative sketches to a series of engravings, designed by an eminent artist. In performing my part of the work I have thrown the Mammalia into twenty-four groups-corresponding more or less to the picture designs-and have dwelt chiefly on the geographical distribution of the animals. The Cetaceae and Vespertilionidae are properly omitted. In the groups given there is attempt made at any very scientific arrangement. The sketches are purely of a popular character, even the scientific menclature being avoided. It is hoped, however, that they may prove of service to the zoological tyro, and form as it were his first stepping-stone to a higher order of classification. In reality, twithstanding the prodigious speculations of learned anatomists, truly good arrangement of the Mammalia has yet been arrived at; the deficiency arising from the fact that, as yet, true zoologist has had the opportunity of a sufficiently extended observation of the natural habits of animals.