560 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



Micrastur Gray, List Gen. Birds, ed. 2, 1841, 6; Gen. Birds, i, 1844, 28, pi. 10, 



fig. 1. (Type, FaJco brachypterus Temminck = Sparvius melanoleucus 



VieUlot.) 

 Climacocercus Cabanis, in Wiegmann's Arch, fiir Naturg., 1844, Bd. 1, 265. 



(Type, by original designation, Falco brachypterus Temminck = Sparvius 



melanoleucus Viellot.) 

 Climacourus (emendation) Bonaparte, Consp. Gen. Av., i, 1850, 30. 

 Rhyncomegas Bonaparte, Compt. Rend., xxxvii, 1853, 809. (Type, by mono- 



typy, Falco brachypterus Temminck = Sparvius melanoleucus Vieillot.) 

 Rhynchomegus (emendation) Bonaparte, Ann. Sci. Nat., s^r. 4, i, 1854, 111; 



Rev. et Mag. ZooL, vi, 1854, 537. 

 Rhyncomegus (emendation) Ridgway, Proc. Boston Soc. Nat. Hist., xvi, 1874, 73. 

 Nothierax Sundevall, Ofv. Vet.-Akad. Forh., xxxi, No. 2, 1875 (1874), 25. 



(Type, by monotypy, Falco xanihothorax Temmmck = Sparvius ruficolHs 



Vieillot.) 

 Thrasyaccipiter Bertoni, Aves Nuevas Paraguay, 1901, 164. (Type, by mono- 



typy, T. seminocturnis BeTtom = Sparvius ruficollis Vieillot.) 



Falconine hawks (Falcones) with the general aspect of Accipiter, 

 but differing (besides osteologically) in scutellation of tarsi and in 

 possessing a "facial ruff" (as in Circus); size variable, from rather 

 small to rather large (wing 165-298 mm., tail 160-331 mm.). 



Bill relatively short, deep, and compressed, its depth at base greater 

 than distance from anterior edge of nostrils to tip of maxilla and 

 much greater than its width at same point; culmen very strongly 

 and regularly decurved, the tip of maxilla strongly and sharply un- 

 cinate; maxillary tomium more or less distinctly sinuate; mandibular 

 tomium slightly but distinctly convex, the tip of mandible truncated, 

 presenting, in front view, a conspicuous V-shaped notch; gonys dis- 

 tinctly (more or less strongly) convex, rather prominent basally, 

 through contraction of mandibular rami; cere with anterior outline 

 very strongly sinuate, convex in front of nostril, thence strongly 

 receding below toward rictus, the portion above nostril also, but to a 

 far less extent, producing a more or less concave outline across base 

 of culmen. Nostril moderate in size to rather large, elliptically oval, 

 ovate, or nearly circular, its longer axis more or less oblique, close to 

 anterior edge of cere, without definite anterior margin (except as 

 formed by that of cere), without central bony tubercle. Wing rela- 

 tively short, much rounded, longest primaries exceeding secondaries by 

 (usually very much) less than length of tarsus; fourth, jBfth, and sixth 

 primaries (from outside) longest and subequal, the first (outermost) 

 shorter than distal secondaries; inner webs of outer five or six very 

 slightly sinuated, the outer webs of second to seventh or eighth slightly 

 sinuated. Tail decidedly shorter to slightly longer than wing, strongly 

 rounded, the graduation sometimes nearly equal to length of tarsus, 

 but usually much less; rectrices (12) rather broad, with rounded tips. 

 Tarsus a little less to shghtly more than one-third as long as wing, the 

 extreme upper portion feathered in front, covered with large longi- 



