VOL. XVII, PP. 21-50 MARCH 10, 1904 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



A REVISION OF THE NORTH AMERICAN MAINLAND 

 SPECIES OF MYIARCHUS. 



BY E. W. NELSON. 



The present paper covers all of the species and subspecies of 

 Myiarchus known to occur on the mainland of North America 

 north of the Isthmus of Panama. In addition I have included 

 the birds of Cozumel Island near the coast of Yucatan, and the 

 Tres Marias Islands off the coast of Tepic, western Mexico. 



The recently accumulated material in this group, especially 

 the Mexican series in the Biological Survey collection, serves 

 to throw much light upon the characters, relationships and 

 distribution of several obscurely known species. In addition 

 to the large series of specimens available in the Biological Sur 

 vey and National Museum collections, Mr. William Brewster 

 and Mr. Outram Bangs have kindly sent me material from their 

 collections that has been of great value in filling gaps and 

 enabling me to reach definite conclusions in some otherwise ob 

 scure questions. 



The genus Myiarchus appears to reach its greatest develop 

 ment in the American tropics, including the West Indies, with 

 a limited number of forms ranging well up into temperate 

 North America. These most northerly representatives of the 

 genus are cinerascens which reaches the northern border of the 

 Upper Sonoran zone on the west coast in Oregon, and crinitus 

 3 PROC. BIOL. Soc. WASH. VOL. XVII, 1904. (21) 



