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PREFACE. 



This Synopsis is an attempt to bring together all the forms of 

 North American Mammals that have been described, and which are 

 generally considered as entitled to some kind of recognition. All 

 those inhabiting North America and its adjacent seas between the 

 North Pole and the United States and Mexican Boundary have been 

 included. 



It is very manifest to many Naturalists that too many forms have 

 been given distinctive rank, and without doubt a considerable num- 

 ber of the so-called species and subspecies contained in this volume 

 will eventually swell the list of synonyms, already sufficiently for- 

 midable. In late years there has been an evident inclination among 

 some Mammalogists to unduly magnify, as it would seem, trivial dis- 

 similarities observed among their specimens and thus greatly increase 

 the number of slightly differentiated individuals elevated to a separate 

 rank, at the risk of reducing the science to one founded on labels 

 and localities, instead of distinctive and prominent characters, and 

 thus a knowledge of the place where an e.\ample was obtained be- 

 comes at times of more importance for its identification than are the 

 differences that may separate it from its allies. The lack of resem- 

 blances often observed among crania is frequently but the individual 

 variations of a type, and taking these for the characters upon which 

 to establish a new species is apt to lead into error, and in not a few 

 instances too much reliance has been placed upon such slight differ- 

 ences. The same ma\' be said of shades of color, and not a few 

 names in this Synopsis have been given to specimens so closely alike, 

 that one author, in speaking of his Key which was intended to be the 

 means for distinguishing the species, has been obliged to say: "It 

 will be necessary to have both skins and skulls in hand, and even then 

 /'/ U'lN b( impossible to identify some of the forms without actual comparison 

 'iOilh their nearest allies."* The scientific value of such species (?) can 

 only be very questionable at the best, and the elevation to a separate 

 distinctive rank of such intimately related creatures, can not be con- 

 sidered as helpful or beneficial to Mammalogical Science. It can be 

 safely asserted that there is hardly a genus of North .Vmerican Mam- 

 mals that does not contain too many named forms, and that the 

 science would be benefited if a considerable number were relegated 



•Bailey; Revision of Am. \"ol<^s of the genus Microtus. K. .^m. Fawn., No. i 



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