NOTE. XVII 



The analytical keys of the present work are on the same plan as 

 those in the author's Manual of North American Birds;' that is, 

 the diagnostic characters of all subdivisions are contrasted in dichoto- 

 mous series of antithetical phrases. Many modifications of this plan 

 and others essentiallj^ different have been experimented with or tested, 

 but none have been found to possess equal simplicitj'^ of construction 

 or facility of practical use. The keys of the present work differ from 

 those of the Manual in this respect, however; the latter are a com- 

 bination of "key" and diagnosis, while the former consist entire!}' of 

 a key based only on the exclusively diagnostic characters. Although 

 the plan of these keys is so simple that directions for their use seem 

 hardly necessarj^ it may be as well to explain the method of their use. 

 The dichotomous characters are arranged alphabetically, thus, "a" is 

 the antithesis of "aa " , ' ' ^ " that of " 55 ", etc. ; therefore if the characters 

 mentioned following- "a " do not apply to the specimen in hand then 

 they must be sought for under after "aa". It will, of course, be 

 found that either the characters following "a" or those following "aa " 

 do apply, unless the specimen happens to be a new species or the key 

 to the wrong genus (or other group) is being used. When its posi- 

 tion as to "a" or "aa" has been fixed, the next step is to find whether 

 it belongs to "5" or " W under "a" or "aa," as its position may 

 have been determined; then whether in "c" or '■''cc,^'' and so on, or 

 until the species or subspecies is "run down.'"' 



The names of colors used are those of the author's Nomenclature of 

 Colors.' 



' A I Manual |. of | North American Birds. | By | Robert Bidgway. | — | Illustra- 

 ted by 464 outline drawings of the | generic characters. | — | Philadelphia: | J. B. 

 Lippincott Company. | 1887. | 



Royal 8 vo, pp. [i]-xi, 1-631, pis. i-cxxiii. 



(Second edition, revised, with new preface and appendix, published 1896.) 



' I A I Nomenclature of Colors | for Naturalists, | and | Compendium of Useful 

 Knowledge | for Ornithologists. | By | Robert Ridgway, | Curator Department of 

 Birds, United States National Museum. | With ten colored plates and seven plates | 

 of outline illustrations. | Boston: | Little, Brown and Company. | 1886. | 



17024—01 II 



