EXPLANATION OF THE WORK 



The present work is intended to include all the species and sub- 

 species of birds known to occur in North America (from the Arctic 

 Islands, Greenland and Alaska, southward), Middle America (including 

 Mexico and Central America), the West Indies and Islands of the 

 Caribbean Sea, South America and adjacent islands of the Atlantic 

 and Pacific oceans having fauna! relationship. 



In the synonymies of this work the references are largely confined 

 to the original descriptions (with type localities), the Catalogue of 

 Birds of the British Museum, Ridgway's Birds of North and Middle 

 America (Bull. U. S. National Museum, No. 50), monographs of fam- 

 ilies and genera, works containing colored plates of the various species, 

 and important papers in relation to geographical distribution, but 

 in many cases, where numerous nomenclature! changes have been made 

 by authors, the more important combinations and variations are given. 

 A slight departure from the orthodox method is that of always giving 

 the reference to the accepted original description first, so that the type 

 locality, which follows it in parenthesis, may be noted at a glance. 

 Diagnostic descriptions will be given of all species and subspecies not 

 included in the standard works, Ridgway's Birds of North and 

 Middle America and the Catalogue of Birds of the British Museum, 

 and for this reason Part II of this work is issued first, leaving Part I 

 (containing the "Water Birds," Galliformes, etc.) to be completed and 

 issued after the parts containing those Orders in Prof. Ridgway's great 

 work shall have been published, thereby reducing the size of this work 

 by largely diminishing the number of forms which would otherwise 

 require descriptions, and enable the writer to conform (so far as pos- 

 sible) to the nomenclature, conclusions regarding specific and subspecific 

 evaluations, and the vernacular names of North and Middle American 

 forms, adopted therein, and also to allow more time to devote to the 

 critical study of a number of families of the so-called "Water Birds, " 

 especially from South America, many species not previously repre- 

 sented in the Museum's collection having been secured by expedi- 

 tions during the past few years. 



In the following pages the presence of an * preceding the name of 

 a species indicates that it is represented in the Field Museum collection 

 by one or more specimens and when duplicates are available for ex- 



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