231 



Genera and subgenera of Polyboei. 



A. — Tarsus ^-f its length longer tlian the middle toe ; outer toe but 

 little longer than the inner; posterior toe very decidedly shorter 

 than the inner ; claws slightly curved, blunt. Inner webs of 

 primaries deeply sinuated. Habits chiefly terrestrial. 



a. Nostril linear, obliquely vertical, its tubercle concealed. 



1. PoLYBORUS. Nostril linear, obliquely vertical, its posterior 

 end the upper one ;* situated in the upper anterior corner of 

 the cere. Anterior outline of the cere nearly straight and 

 vertical. Occipital feathers elongated into a depressed crest. 



b. Nostril circular, in the middle of the cere, its tubercle exposed; f an- 



terior outline of the cere doubly curved. 



2. Phalcob^nus. Toothandnotchof the tomia of the bill near- 

 ly obsolete ; lower jaw nearly naked ; outer toe not apprecia- 

 bly longer than the inner; posterior toe reaching much be- 

 yond the first joint of the middle toe; claws remarkably blunt, 

 slightly curved ; posterior face of the tarsus without distinct 

 rows of quadrate scales; upper tail-coverts remarkably de- 

 veloped, covering nearly two-thirds the tail ; size large. 



a. Frontal feathers (of adult) recurved, very soft, lanceolate ; 

 loral and maxillary regions naked; fore-neck feathered. 

 In the adult, the abdomen, anal region, crissum, upper tail- 

 coverts, and lining of the wing white; secondaries and tail 

 tipped with white; other parts deep black. .Phalcobcenus. 



fi. Frontal feathers pointed backward (normally), stiff and 

 lanceolate ; lower jaw and lores densely covered with 

 strong bristles ; fore-neck naked. In the adult,abdomen and 

 anal-region ochraceous; crissum and upper tail-coverts 

 black ; lining of the wing and tibiae black mixed with ochra- 

 ceous; breast and nape longitudinally streakedwith dingy 

 whitish ; secondaries not tipped with white Senex^ 



3. MiLVAGO. Tooth and notch of the tomia of the bill distinctly 

 indicated ; lower jaw normally feathered ; outer toe decidedly 

 longer than the inner; posterior toe not reaching the first 

 joint of the middle toe; claws sharp, strongly curved (as in 

 the Falcones) ; posterior face of the tarsus with two distinct 

 rows of quadrate scales. Upper tail-coverts normal, covering 

 about one-third the tail ; size small. 



B, — Tarsus scarcely longer than the middle toe; outer toe very much 

 longer than the inner, which is but little longer than the posterior 

 one. Inner webs of primaries shallowly sinuated. Habits 

 strictly arboreal. 



4. Ibyctee. Nostril circular, near the middle of the cere, its 

 tubercle either concealed or exposed; anterior outline of the 

 cere doubly curved. Tarsus without transverse scutellse 

 either in front or behind. 



a. Size large. Bill slender, the tip much produced ; gonys 

 barely convex, nearly horizontal. Bare superciliary 

 region very narrow. (See Plate X VIII, Fig. 1.) . . Ibycter. 



/?. Size small. Bill thick, the tip only slightly produced ; 

 gonys strongly convex, decidedly ascending terminally. 

 Bare superciliary region very wide. (See Plate XVIII, 

 Fig. 2.) Daptrius. 



* This is exactly the reverse of the position of the nostril in all other FalconidcB, in which 

 its direction is oblique ! tAs in the Falcones ! 



