FALCONID.E — THE FALCONS. 



191 



than, equal to, or longer than, the fourth ; two outer primaries with inner webs sinuated. 

 Tail with the outer pair of feathers more than twice as long as the middle pair. 



The genus contains but a single species, the N. forficatus, which is pecu- 

 liarly American, Ijelonging to the tropical and subtropical portions on both 

 sides of the equator. The species is noted for the elegance of its form and 

 the beauty of its plumage, as well as for the unsurpassed easy gracefulness 



62994, 3 . 



Naiidenis forficatus. 



of its flight. It has no near relatives in the Old World, though the widely 

 distributed genus Milvus represents it in some respects, while the singular 

 aenus Chelidinia, of Africa, resembles it more closely, but is much more 

 intimately related to Idinia and Elanus. 



Species. 

 N. forficatus. Head, neck, entiri; lower surface, and band across the 

 rump, inimaculale snowy-white ; upper surface plain polished blackish, with 

 varying lights of dark purpli.sh-bronze (on the back and shoulders) and 

 bluish-slaty, with a green reflection in some lights. Young, with dusky 

 shaft-streaks on the head and neck, and the feathers of the upper parts 

 margined with white. Wing, 15.40 - 17.70 ; tail, 12..50- 14.50; culmen. 

 .70 -.80; tarsus, 1.00-1.30; middle toe, 1.15-1.20. Hab. The whole of 

 tropical, subtropical, and warm-temperate America. Accidental iu Eng- 

 land. 



