266 FALCONID.E FALCO 



d*. Nostrils horizontal ovals, tarsus 

 with small rounded or polygonal 

 scales ; tail only slightly forked 



or square Elanus, p. 339. 



e 4 . Nostrils oblique slits, tarsus 

 covered with small polygonal 

 scales ; bill very weak, com- 

 pressed and keeled MachcerJiamphus, p. 344. 



i 1 . Lores and a space round the eye naked 



without bristles or feathers. 

 a?. Tail moderate, about one-third the 



length of the wing. 



a 3 . Bill compressed and slender and 

 without festoon, tarsus covered 



with small hexagonal scales GypoMerax, p. 318. 



6 3 . Bill stout, edge of the upper mandi- 

 ble distinctly festooned, tarsus 

 with three or four transversely 



enlarged scutes Haliaetus, p. 309. 



6 2 . Tail very short, about quarter length 

 of wings ; tarsus covered throughout 

 with swollen and rounded scales ... Helotarsus, p. 314. 

 c 1 . Lores covered with small scale-like 



feathers, no bristles Pernis, p. 345. 



Genus I. FALCO. 



Type. 



Palco, Linn. Syst. Nat. i, p. 124 (1766) F. peregrinus. 



Bill strong, sharply down-curved and hooked ; edge of upper 

 mandible with a well-marked tooth behind the hook and often a 

 festoon as well ; nostrils round, with central tubercle ; wings long 

 and pointed, reaching nearly to the tip of the tail, third primary 

 usually the longest; difference between the primaries and secon- 

 daries more than half the length of the tail ; tail slightly rounded ; 

 tarsus about as long as the middle toe without claw, upper third 

 feathered in front, bare portion covered with hexagonal scales which 

 are rather larger in front ; toes all very long, the outer one longer 

 than the inner ; claws much curved and sharp. 



This genus, containing the true Falcons, is cosmopolitani, being 

 found throughout the world except in the Pacific Islands. Some 

 twelve species have been noticed in Africa, five of which reach our 

 limits. 



