FAMILY TROCHILIDAE 327 



to the lower Rio Magdalena. Throughout this great area the birds 

 appear uniform, aside from the usual amount of individual variation. 

 In the extensive series of specimens now available the supposed 

 differences on which Todd proposed a race for the Caribbean popula- 

 tion east to the Canal Zone are not valid. 



AMAZILIA EDWARD (De Lattre and Bourcier) : Snowy-breasted 

 Hummingbird, Colibri Pechiblanco 



Rather small ; head and foreneck dark green ; back bronze-green 

 to coppery bronze ; breast and abdomen clear white. 



Description. — Length 92-100 mm. Adult male, crown, hindneck 

 and upper back metallic green ; lower back, rump, upper tail coverts 

 and greater to lesser wing coverts bronze-green, bronze or coppery- 

 bronze ; tail black to coppery bronze or tawny-brown (varying ac- 

 cording to subspecies) ; wings, including primary coverts, dusky, 

 glossed with purple to coppery brown ; cheeks, foreneck, upper breast 

 and sides glittering yellowish green, with feathers of foreneck and 

 breast basally white; lower breast and abdomen pure white; under 

 tail coverts dull gray centrally, bordered with white to cinnamon-buff ; 

 under wing coverts coppery green to green ; edge of wing pale buff 

 to cinnamon-buff. 



Adult female, similar, but colors a little duller. 



This is a common, widely distributed species mainly of the Pacific 

 lowlands, usually found feeding at flowers. In the western area east 

 to western Code, and including the eastern side of the Azuero 

 Peninsula, individuals uniformly are slightly duller colored on the 

 back, with the tail mainly bluish black. Through the western sector 

 of the Province of Panama they become progressively brighter bronze 

 to coppery bronze on the back, with the tail changing to coppery- 

 brown, dull rufous-brown, or to bronze-brown. The species is 

 distributed also throughout the islands of the Archipielago de las 

 Perlas, where the individuals are duller colored, more like those of 

 western Panama. 



In summary, the western population, niveoventer, is fairly stable 

 in color characters over a broad area. Those of the eastern half of 

 the Republic have brighter dorsal hues, and are more variable. There 

 is intergradation between the two main groups over a somewhat re- 

 stricted area in eastern Code and adjacent western Province of 

 Panama. As specimens accumulated in earlier years the variations 

 noted above were evident so that several forms were described. 

 With the larger, better distributed series now available a clearer view 



