INTRODUCTION 



the accumulated collections of all the large museums. The 

 reviser has borrowed all the available material he could find, 

 and the insight he has secured makes his conclusions of much 

 greater value than those of one who works with only a few 

 specimens. I have cited these monographs throughout the 

 book, and it may be stated that in many cases I have quoted 

 or paraphrased directly from these works. The reviser, with 

 his wealth of material, has chosen the most typical specimens 

 as the basis for each description, and this is an aid in avoiding 

 extreme examples. The description may be regarded more 

 or less as a norm which is as often exceeded as not reached in 

 the development of any character. Incidentally, I have had 

 access to the fairly large and complete collection of North 

 American mammals in the American Museum and have taken 

 much data directly from the skins. 



Common Names 



While every mammal known to science has a scientific name, 

 it does not follow that it has a vernacular or common name. 

 On the contrary, only a small percentage of our mammals have 

 good, distinctive, common names that serve to identify the 

 different species and subspecies in large groups which may be 

 represented by half a hundred species and subspecies. For 

 example, consider the Chipmunks. Even a casual observer 

 will recognize, in visiting different parts of the country, that 

 there are many distinct varieties of Chipmunks. Yet he will 

 find that in most sections the people know only the one name 

 for the creature — 'Chipmunk. Popular interest in precise, 

 common names for mammals has not reached the stage where 

 qualifying adjectives have been applied to the group names. 

 Wherever common names exist and can be used to clearly 

 designate mammals, they have been taken for this volume. 

 Some mammalogists, when they describe a species new to 

 science and properly label it with a Latin name, have given 

 at the same time an English common name. But most mam- 

 mals either have not received convenient popular names or 

 have been christened with stilted or poorly chosen names such 

 as are little likely to come into general usage. A common 

 name, to come into popular favor, must be sufficiently apt 

 and descriptive to make recollection an easy matter; it must 



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