PREFACE 



This synoptic key is an introduction to the classification of the 

 animal kingdom and to the general reference books most used by 

 teachers and high-school or college students in identifying an 

 unknown animal. The key is based on books of wide circulation 

 and is intended for the use of persons who are not expert system- 

 atists but who must make excursions into this field, much neg- 

 lected in modern zoological training. It is hoped that this com- 

 pilation may make such excursions less laborious and more 

 profitable, and that particularly it may encourage the introduction 

 of exercises in classification of common animals into elementary 

 courses in zoology. 



The form used is based on that in Ward and Whipple's Fresh- 

 Water Biology. The number introducing each key paragraph is 

 followed by numbers in parentheses indicating possible alternative 

 choices. When a choice is made, the next step is indicated by the 

 number or other direction immediately following. Page refer- 

 ences are given to general taxonomic works in which the classifica- 

 tion may be further traced. Unusual or technical terms are 

 explained in the glossary. 



The key is based on a compilation made over fifteen years ago 

 by Professor V, E. Shelford, who has kindly consented to its 

 publication. The content has been much changed; the form 

 recast; and the references brought up to date by the present 

 compiler, who takes entire responsibility for the accuracy of this 

 version. I wish here to express my thanks to the many students 

 and laboratory assistants who have called attention to errors in 

 the mimeographed copies; to all aythors who have contributed 

 knowingly or otherwise; and particularly to Professor H. S. Pratt 

 for permission to use largely from his Manual of Common Inverte- 

 brates. I am sorry that his forthcoming Manual of Vertebrates is 

 not yet available. 



