PREFACE. Vll 



5. Work in Zoology, once begun, should continue for a 

 whole year if possible. 



If we may judge from the diversity of texts which have ap- 

 peared in the last fifteen years, there are some important points 

 yet undetermined. Some of these are : 



1. What Zoology is of most worth? Which of the numerous 

 divisions of the subject should receive greatest stress in a first 

 course? Should a preponderance of attention be given to the 

 study of structure and to dissections ? Or to a comparison of 

 the various ways of performing the functions necessary to all 

 animals ? Or to the study of the classification of animals into 

 their families and species ? To the economic value of animals ? 

 Or to the study of their relations to each other, and to the plant 

 kingdom, and to the inorganic environment? Text-books of 

 the last fifteen years have passed through several distinct 

 phases in the effort to find an answer to these questions. 



2. What proportion of such a course should be given to the 

 descriptive and theoretical, and what to the practical or labo- 

 ratory aspects of the subject? 



3. What should determine the order of presentation of the 

 subject, logic or expediency? and what is expedient? 



The present book is intended as a suggestion in the direction 

 of an answer to some of these questions. The plan of treat- 

 ment here recommended has been followed by the author in 

 his own classes for a number of years. By its use he has 

 secured good interest and fine spirit, in the study of animals 

 and animal life, on the part of beginners ranging from the 

 third year of the preparatory school to freshmen in the college. 



The following principles have guided in the selection and 

 the arrangement of the material of the present volume : 



i. A first course should really be a foundation course, and 

 as such should give the student a broad and catholic view of 

 the whole subject, without thereby becoming commonplace. It 

 should utilize all the main departments of Zoology, because 

 each department contains matter which should be familiar to 

 all persons of ordinary education. Furthermore, the depart- 



