PREFACKH 
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 selec- 
tion 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 
reduced the pages of this book to conformity with those of 
other volumes of the series by treating some groups more briefly 
than others. It has appeared to me to be desirable to treat fully 
such groups as the Edentata and the Marsupialia, and permissible 
to be more brief in dealing with such huge Orders as those of the 
Rodentia and Chiroptera. Lengthy disquisitions upon such 
familiar and comparatively uninteresting animals as the Lion and 
Leopard have been curtailed, and the space thus saved has been 
devoted to shorter and more numerous accounts of other creatures. 
As there are nearly six hundred genera of living Mammals known 
to science, omission as well as compression became an absolute 
necessity. I have given, I hope, adequate treatment from the 
standpoint of a necessarily limited treatise to the majority of the 
more important genera of Mammals both living and extinct; but 
the length of this part of the book had to be increased by the dis- 
coveries, which give me at oncé an advantage and a disadvantage 
as compared with the two authors whose names I have quoted, of 
a considerable number of important new types in the last ten years. 
