Inasmuch as Sir W. H. Flower and Mr. Lydekker could not profess to treat the Mammalia exhaustively within the limits of nearly 800 pages, in their Introduction to the Study of Mammals , it is obvious that the present volume, which appears ten years later and is of rather less size, can contain but a selection of the enormous mass of facts at the disposal of the student of this group. Thus the chief question for myself was what to select and what to leave aside. It will be observed that I have re