PEEFACE 



TO THE FIFTH EDITION. 



This book is designed to give to students and collectors 

 a ready means of identifying the Vertebrate fauna of the 

 region which it covers, and of recognizing the characters 

 on which the families, genera, and species of these ani- 

 mals are founded. 



To these ends, I have made use of a system of analyti- 

 cal keys by which differential characters are brought into 

 contrast. The usefulness of such keys- has long been 

 recognized by botanists, and in ornithology the recent 

 works of Coues and Ridgway have proved their value to 

 the student. 



That the book might not reach a size too large for field 

 or class use, I have made all descriptions very concise, 

 with as few repetitions as possible. I have confined the 

 generic characters to the analytical keys, using as a rule 

 only such characters as are distinctive as well as descrip- 

 tive. The need of condensation has caused the omission 

 of synonymy, and of references to authorities except in 

 special cases. 



In the first four editions of this work (1876, 1878, 1880, 

 1884), large use was made of ai'tificial characters in the 

 analyses of the genera. The use of such characters is 

 often a help to quick identification of species, but with 

 the disadvantage of hiding from the student the real char- 

 acters on which classification is based. In the present 

 edition, these artificial keys have been chiefly set aside, 



