A CLASSIFICATION FOR THE BIRDS OF THE 



WORLD 



By ALEXANDER WETMORE 

 Research Associate, Smithsonian Institution 



The principal additions to current information that affect the ar- 

 rangement of the family and higher groups in birds since the previous 

 paper on this subject by the author was published (1951, pp. 1-22) 

 have come in the fossil field and deal in part with the earliest known 

 forms of the Jurassic and Cretaceous periods. While there has been 

 much discussion of family limits among the Passeriformes, with 

 considerable spread of opinion as to family limitations, in the main 

 these have been expressions of individual viewpoint, without com- 

 pletely firm support in the new information offered. Valuable new 

 data that are accumulating from many sources relative to this order, 

 where they are completely decisive, in the main suggest better align- 

 ment of existing families through shift of genera from one group to 

 another. The great majority of the many species still require detailed 

 anatomical study. 



Under the revision of the International Code of Zoological Nomen- 

 clature as adopted at the Fifteenth International Zoological Congress 

 held in London in July 1958, now in press, a new rule provides that 

 family names are to be based on strict priority in publication. There 

 is no attempt to follow this requirement in the classification presented 

 herewith since the final draft of the Code was not yet in print when 

 the paper was under preparation. It is apparent, however, that ac- 

 ceptance of this new proviso, while intended to establish stability, in 

 the beginning will bring many changes in current family and higher 

 group designations in the class Aves. 



The following notes that discuss the more important changes are 

 added to material from the introductory section of the revision of 1951 

 where this remains pertinent. In the classification at the end of the 

 text the fossil groups are enclosed in brackets to enable their ready 

 recognition on the part of students familiar mainly with the family 

 and other categories of living kinds. 



Archaeornithes. — The recent careful study of the specimen of 

 Archaeopteryx in the British Museum (Natural History) by Sir 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 139, NO. 11 



