PREFACE TO FOURTH EDITION. VII 



Nomenclature. The International Code of Nomenclature 

 which corresponds closely with the A. 0, U. Code has been 

 adopted as a basis for the nomenclature of the Check-List but 

 where the latter Code is more explicit and carries its rulings to 

 further detail it has been followed. Cases not explicitly covered 

 by the Codes have been decided by a majority vote of the Com- 

 mittee without attempting to formulate definite rules. 



Accidental and Introduced Species. Species known to breed or 

 occur regularly anywhere within the area covered by the Check- 

 List are included without comment but those of only casual or 

 accidental occurrence are marked with a star. In former editions 

 they were enclosed in brackets but the present method seems to 

 distinguish them more definitely. Species introduced by man 

 into North America are marked with a double star. Convenience 

 seemed to be best served by including all such species in the reg- 

 ular List rather than arranging them in separate categories. 



Foot Notes. Much explanatory matter is presented in foot 

 notes with the idea of amplifying the text. Such matter consists 

 of mention of the more important additional races or suggested 

 changes of names which have not been accepted or adopted by 

 the Committee so that those who may not agree with the decisions 

 of the Committee may have this information before them. It 

 would be understood however that this information is by no 

 means complete. 



In the case of species which are included in the Check-List 

 wholly on the ground of accidental or casual occurrence the dates 

 of occurrence are given so far as possible with footnote references 

 to the place of publication of the records upon which their inclu- 

 sion is based. 



Technical Names. After careful consideration the Committee 

 decided to abandon the specific "group names," introduced in the 

 third edition, at the head of each series of subspecies, for example 

 Melospiza 7nelodia at the head of the Song Sparrows, as it seems 

 to have occasioned more confusion than benefit. It is obvious 

 from the inclusion of the name melodia in the middle of each 

 trinomial that all of them are regarded as subspecies of that one 

 species and the additional binomial heading seems superfluous. 

 If anyone wishes to refer to a Song Sparrow without identifying 

 it supspecifically he may use the term ^^ Melospiza melodia subsp." 



