FALCOXID.E- THE FALCONS. 249 



oval, liorizontal, with an exposed cartilaginous tubercle. Lores nearly naked, with scant 

 bristles. Wing long (much as iu Duteo) ; the fourth or lifth quill longest, and the first 

 shorter than the eighth to the tenth ; outer four with inner wBbs sinuated. Tail long, 

 more than two thirds the wing; even or slightly rounded. Feet robust, when outstretched 

 reaching nearly to the eud of the tail ; tarsus nearly twice the length of the middle, very 

 robust, the frontal and jiosterior rows of scutelke very distinct; outer toe longer than the 

 inner ; claws strong, well curved, and acute. Sexes alike ; young and old plumages very 

 diflerent. 



This genus includes a single species, tlie /•'. unicinctus, with its two climatic 

 races, unicinvtus of South America and harrisi of Mitldle America. -It is 

 most nearly related to the genus Uruhitiivja, of tropical America, the species 

 of wliicli are sluggish and almost Caracara-like in their habits, though they 

 are hardly more so than our own Butconcs. The genus Craonvex of Gould 

 having been tbuuded upon Butco galajiagoensis, a species strictly congeneric 

 with B. horealis, it is necessary that a new generic name should be instituted 

 for the present species, since it so well merits separation to that rank. I 

 accordingly propose the name given at the head of this chapter. 



Species and Races. 

 P. unicmctus. Wiug, 11.U5- U.liO : tail, 9.UU - ll.UU; culmen, .82 - 1.10; 

 tarsus, 2.78- 3.75; middle toe, 1.52 - 2.00. Adult. General color brownish- 

 black or blackish-brown, uniform, or slightly variegated by liglit spotting ; 

 the lesser wing-coverts and tibiaj deep rufous, or chestnut. Tail black ; the 

 end and base white, as are also the tail-coverts. Young. Plumage greatly 

 variegated. Above blackish-brown, the feathers edged with rusty ; head 

 and neck streaked with pale ochraceous. Lower parts pale ochraceous or 

 yellowish- white, the breast and abdomen with longitudinal ovoid spots of 

 blackish ; tibi<e with transverse bars of dark rusty ; lower tail-coverts with 

 black shaft-streaks. Lesser wing-covert region only washed with rufous. 

 Tail grayish-brown, whitish at the tip, and crossed by narrow bands of 

 dusky. 



Adult with the blackish much broken up by lighter spotting. Wing, 

 11.65-14.60; tail, 9.00 - 10.50 ; culmen, .82- 1.02 ; tarsus, 2.78-3.40; 

 middle toe, 1.52-1.85. Hah. South America . . \ar. unicinctiis} 



1 Falco unicinctus, Te.mm. PI. Col. 313, 1820. MorpUnus uniciitclii.':. Less. Man. Orn. I, 1828, 

 90. Jslur unicinctus, Cuv. Keg. An. (ed. 2), I, 1829, 332. — Strickl. Orn. Syn. I, 221.— 

 Kaup, Monog. Falc. 1850, p. 66. Buleo unicinctus, Gr.\y, List B. Brit. Mus. 18. — Ib. Hand 

 List, 1, 7, No. 55. Nisus unicinctus, Less. Tr. Orn. p. 61. Hi/pomoi-phmis unicinctus, Tsciium, 

 Fauna Per. pp. 17, 85. Spizagcranus unicinctus, Kaitp, Ueb. Senck. 1845, 260. Urubitinga 

 unicinda, Lafr. Rev. Zobl. 1849, 99. — Pelz. Om. Bras. 1, 1868, 3, No. 10. — 1b. IV, 1871, 

 394. Polybwrus tccniurus, TscHUDi, Av. Consp. Wiegm. Arch. .1844, 264. — 1b. Fauna Per. pi. 

 ii, Juv. It seems that the South American birds of this species never attaiu the simple tricolored 

 plumage as.sumed by the adult of the North American form, Temminck's figure (PI. Col. 313) 

 representing the nearest approach to it that 1 liave seen, in a large series of adult specimens. 

 The following descriptions show the average adult of var. unicinctus: — 



Adult male (No. 13,908, Chile ; Lieutenant Gilliss). Resembling the innuature of var. harrisi, 

 as described on p. 1569 (No. 56,763). Primaries edged terminally with whitish ; inner webs 

 of tail-feathers mottled whitisli for their basal half, not showing the regular transverse bars seen 

 in the immature of var. harrisi ; under' surface of primaries almost wholly white, becoming 

 ashy, barred with dusky, towards their ends. Wing, 12.00 ; tail, 8.30 ; tarsus, 2.90 : middle 



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