298 



NORTH AMERICAN BIRDS. 



both of which belong to North America, one of them (A. lagopus) being 

 found also in Europe and Africa. These differ very considerably from each 

 other, in the details of external structure, probably quite as much as they do 



34.338,f-,. 



d4338, f 



54338, 



54338,^ 



54338, Archibuteo lagopus. 



64338,^ 



41720, A. ftrrugineua. 



from the Asiatic forms above mentioned. The following synopsis will ex- 

 press the differences between the two North American species, and between 

 the American and European races of the one common to both continents. 



Species and Races. 



Common Characters. Tail more or less white basally ; inner webs of the pri- 

 maries white, without bars, anterior to their emargination. Head and neck 

 with longitudinal streaks of whitish and dusky (except in melanistic individuals 

 of lagopus var. sancti-johannis). 



1. A. ferrugineus. Wing, 15.90-17.60; tail, 9.50-11.00; culmen, 1.00- 

 1.20; tarsus, 3.10-3.45; middle toe, 1.40-1.65. Bill wide, the base very 

 broad and depressed. Beneath, continuous pure white, without conspicuous 

 spots, except sometimes a few scattered ones along the sides and across the 

 abdomen ; breast immaculate, or with only narrow shaft-streaks. Upper 

 parts always with more or less rufous. Adult. Upper parts and tibiae 



