PREFACE 



THIS book is intended to serve as a text for beginning students 

 in universities and colleges, or for students who have already 

 taken a course in general biology and wish to gain a more com- 

 prehensive view of the animal kingdom. It differs from many 

 of the college textbooks of zoology now on the market in several 

 important respects : (i) the animals and their organs are not 

 only described, but their functions are pointed out ; (2) the ani- 

 mals described are in most cases native species ; and (3) the 

 relations of the animals to man are emphasized. Besides serv- 

 ing as a textbook, it is believed that this book will be of interest 

 to the general reader, since it Ogives a bird's-eye view of the 

 entire animal kingdom as we know it at the present time. 



Within the past decade there has been a tendency for teachers 

 of zoology to pay less attention to morphology and more to 

 physiology. As a prominent morphologist recently said, 

 "Morphology' ... is no longer in favor . . . and among 

 a section of the zoological world has almost fallen into dis- 

 grace " (Bourne). The study of the form and structure of 

 animals is, however, of fundamental importance, and is abso- 

 lutely necessary before physiological processes can be fully 

 understood ; but a course which is built up on the " old-fash- 

 ioned morphological lines " is no longer adequate for the presen- 

 tation of zoological principles. 



In writing this book the author has attempted, not only to 

 describe the most important structural features of the various 

 types of animals, but also to point out the vital phenomena as 

 expressed in the functions of the organs. Furthermore, an 

 endeavor has been made to compare the animals in each phylum 

 with those of the members of nearly related phyla, so that the 



