iv PREFACE 



It is the purpose of this volume to attempt to 

 picture zoology as a unified science. There are ex- 

 cellent books that supply a knowledge of the animal 

 kingdom this one aims to add some knowledge of the 

 science itself. It is, therefore, intended to be a book 

 of collateral reading for courses in practical zoology, 

 and, while written with this primarily in mind, it 

 is, at the same time, adapted to the needs of the 

 general reader who wishes to become familiar with 

 the progress of zoology. 



In the preparation of the material I have been 

 indebted for helpful suggestions to my colleagues, 

 Professor Sidney I. Kornhauser and Dr. Olof Larsell. 

 I am also indebted to the Macmillan Company for 

 permission to use verbatim a considerable portion 

 of my article "Zoology' published by that firm in 

 A Cyclopaedia of Education, 1913. 



WILLIAM A. LOCY. 



