FALCONID.-E — TFIE FALCONS. 253 



Nostril neai-Iy circular, with a conspicuous (but not central or bony) tubercle ; core 

 densely bristled below the nostril, almost to its anterior edge ; orbital region linely bristled. 

 Tarsus very long anil slender, nearly twice the length of the middle toe ; toes moderate, 

 the outer one decidedly longer than the inner; claws very long, strong, and sharp, and 

 curved in about one quarter the circumference of a circle. Tibial feathers short and close, 

 the plumes scarcely reaching below the joint. Feathers of the forehead, gular region, 

 sides, and tibiic, with white filamentous attachments to the end of the shafts. Wing 

 very short, much rounded, and very concave beneath; fourth quill longest; first shorter 

 than ninth ; four primaries emarginated, and one sinuated, on inner webs ; five sinuated 

 on outer webs. Tail about two thirds as long as wing, rounded. Outstretched feet 

 reaching beyond end of tail. 



This genus has no very near relatives among the American Fnkonidce, 

 nor, indeed, among tliose of other portions of the world. It is, perhaps, most 

 closely related to the genus Riipornis, of South America, from which, how- 

 ever, it is very distinct. It is represented by a single species, the type of 

 which, supposed to have come from California, still remains unique. 



The elongated legs, reaching considerahly beyond the rather short tail, the 

 close thigh-plumes, tlie long and extremely acute claws (somewhat like those 

 oi Rostrltamua), with the short, rounded, and very concave wing, are its most 

 striking peculiarities. Besides these distinguishing features, the short, thick 

 bill, \Q.ry deep through the base, and the filamentous attachments to the 

 shafts of the feathers of certain parts of the body, are also very characteris- 

 tic. The latter feature may possibly be a mark of immaturity, but I have 

 seen nothing like it in other Raptores, and it seems to be more analogous to 

 the nuptial ornaments seen in the Cormorants {Phahcrocoracidai). 



Species. 



O. gruberi. Wing, 10.10; tail, G.oO ; culmen, about .80; tarsus, 2.70; 

 middle toe, 1.4.5; posterior claw, 1.00, its digit .80. Immature (?). Uniform 

 grayish-umber, tinged with dull rufous on the neck ; lining of the wing and 

 tibiae dull grayi.sh-oinnamon. Primaries inclining to black, and showing 

 just discernible, obscure hoary bars on their basal half. Tail brownish- 

 gray, with a hoary cast nearer the shaft (not paler at the tip), and crossed 

 with nine or ten narrow bars of dusky, these becoming hardly distinguish- 

 able basally and terminally. Inner webs of the primaries plain white an- 

 terior to their emargination. Head laterally and beneath obsolctely streaked 

 with whitish. Hub. " California." 



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