FALCONID.E — THE FALCONS. 



199 



Specimens are from Santa Clara, California, Fort Arbuckle, Mirador and 

 Orizaba, Mexico, Chile, and Buenos Ayres ; from all points the same bird. 



This species presents a very close resemblance to the E. vielanopterus of 

 Europe, and the most evident specific difference can only be detected by 

 raising the wing, the under side of which is quite different in the two, there 

 being in the European bird no trace whatever of the black patch so con- 

 spicuous in the American species. The primaries, also, on both webs are 

 lighter ash, while the ash of the upper parts in general is darker than in 

 leucurus and invades more the head above, the forehead merely approaching 

 white. The tail is more deeply emarginated, and the proportions of the pri- 

 maries are quite different, the second being much longer than the third, and 

 the first nearly as long as the second, i'ar exceeding the third, instead of 

 being about equal to the fourth. In the vielanoptej^iis, too, the black borders 

 the eye all round, extending back in a short streak from the posterior angle, 

 instead of being restricted to the anterior region and upper eyelid, as in 

 leucurus. 



A specimen of " B. axillaris " from Australia (13,844, T. E. Peale) appears, 

 except upon close examination, to be absolutely identical in all the minutiae 

 of coloration, and in the wing-formula,, with JS. leucurus ; and differs only very 

 slightly in the measurements of bill and feet, having these proportionally 

 larger, as will be seen from the table. Another (32,577, H. Mactier War- 

 field) has the upper parts so pale as to be nearly wdiite. 



A young specimen of E. axillaris differs from that of E. leucurus as 

 follows : the occiput, nape, and dorsal region are stained or overlaid by 

 dull ashy-rufous, instead of dark brownish-ashy ; more blackish on the head. 

 No other differences are appreciable. 



A very characteristic distinction between leucurus and axillaris is seen in 

 the coloration of the inner webs of the secondaries : in the former, they are 

 abruptly lighter than tlie outer webs, often pure white, in very striking 

 contrast to the deep ash of the outer surface ; in the latter, both webs are 

 of about the same shade of ash, which is much paler than in the other race. 

 Occasional specimens of leucurus occur, however, in which there is little 

 difference in tint between the two webs. 



LIST OF SPECIMENS EXAMINED. 



National Museum, 10 ; Philadelphia Academy, 2 ; New York Museum, 2 ; Boston 

 Society, 4; Cambridge Museum, 2; Cab. Gr. N. Lawrence, 2; Coll. R. Ridgway, 2. 

 Total, 24. 



Measurements. 



