PREFACE TO FOURTH EDITION. Xlll 



Statement of Range. In the case of resident species the range is 

 contained in one sentence except for an accidental occurrence 

 which is added separately, but in the case of migrants three sen- 

 tences are employed: (1) breeding range, (2) winter range and 

 migration route, and (3) casual and accidental occurrences. In 

 the wide-ranging Procellariidae however it was thought best to 

 state the limits of the range in one sentence and list the breeding 

 places in another. 



Additional Races. Where there are one or more races of a species 

 in North America and other extrahmital ones the combined range 

 of the latter is given in brackets, in a separate paragraph, if 

 several races are listed, or following immediately after the range 

 if there is but one. This gives the reader the distribution of the 

 species as a whole if such information is desired or if the separa- 

 tion into races is not recognized. 



Numbers. With the adoption of a new classification the se- 

 quence of the numbers originally attached to the species and 

 subspecies has been completely upset but it was thought ex- 

 tremely undesirable to renumber them since the old numbers 

 have been used in marking eggs for the past forty-five years and 

 probably hundreds of thousands of specimens depend upon them 

 for identification. To institute another series of numbers would 

 create endless confusion. Therefore the original numbers have 

 been retained and a concordance or index has been prepared (p. 

 473) in which they appear in numerical order with reference to 

 the page of the present ('heck- List upon which the species re- 

 ferred to will be found. The numbers of species that have been 

 cancelled or removed are placed in brackets with footnote ex- 

 planations. 



Sequence.- — ^The sequence of genera follows the classification 

 drawn up by Dr. Wetmore and Mr. Miller with a few minor 

 changes agreed upon by Dr. Wetmore and the chairman. The 

 sequence of species and subspecies has been determined by the 

 chairman and in most cases follows Ridgway's "Birds of North 

 and Middle America." The subspecies have been arranged as 

 nearly as possible in accordance with their relationship which is 

 also usually geographic. In this connection it should be pointed 

 out that the so-called "typical" subspecies, i.e. the one in 

 which the specific name is duplicated, viz. Alelospiza melodia 



