NATURAL SCIENCES OF PHILADELPHIA. 139 



Family FALCON ID ./.. 

 I. Eye shaded by a projecting superciliary shield* covered with naked akin. 



A. Nostril circular, with a conspicuous central bony tubercle. f 



a. Prominent tooth on commissure; lower mandible truncated, and with a 

 deep notch corresponding with the tooth on the upper. 

 1. A web or membrane uniting the outer and middle toes at their bases. 



Faleoninse. 



B. Nostril not circular, and without bony tubercle. 



a. A "ruff" or circle of short stiff feathers around the face, as in the Siri- 



gidir. 



1. Membrane between toes well developed Gircinte 



b. No ruff. 



1 Membrane well developed... Icc'pitrinse. 



2. Membrane rudimentary. Halistinx. 



II. No superciliary shield. 



G. Middle toe longer than bare portion of tarsus in front Wilvitue. 



D. Middle toe shorter than tarsus in front l'olyborinie.% 



I. Eye shaded by a projecting superciliary shield, covered with bare skin. 

 A. Nostril circular, with a central bony tubercle. 



Subfamily FALCON 1NJE. 



Bill strong, its breadth at base equalling or exceeding its height; upper 

 outline of cere rather lower than base of the culmen ; gonys much arched, 

 the chord of the arch equalling about half that of the culmen. Near the tip 

 of the upper mandible is a prominent tooth on the commissure, and near the 

 end of the lower mandible, which is truncated, is a deep notch correspond- 

 ing ; the end of the upper mandible is compressed, giving the situation of the 

 tooth an inflated appearance when viewed from above. Nostrils circular, with 

 a conspicuous central tubercle. Orbital region bare; projecting superciliary 

 shield conspicuous, arched, but not very prominent. Tail shorter than wing, 

 the feathers hard and stiff. Primaries very strong, elongated, tapering rapidly 

 toward their points; only the first or first and second with their inner webs 

 emarginated. Tarsus never with a single series of transverse scutelhe either 

 in front or behind ; middle toe very r long 



Diagnoses of generic and subgeneric divisions. 

 A. Tarsus with no transverse scuiellse, but, instead, covered with numerous irre- 

 gular small scales ; second quill longest; first always loilger than fourth ; 

 onlj' first emarginated on inner web. 

 a. Middle toe longer than tarsus the latter scarcely feathered below the 

 knee. First quill equal to or longer than third. 



Genus FALCO, Auct. 

 1. First and second quills equal; outer web of second only sinuated; 

 inner web of first emarginated ; of second, sinuated. 

 Sp. peregrinus, Gmel., and "anatum," Bonap., (= peregrinus var. analum. 



* This "shield" is formed by the bony process of the lachrymal projecting backward 

 over the orbit. In Faleoninse (only) it consists of a single nanow process: in the other 

 subfamilies, it is broader, and composed of two separate pieces, with cartilaginous junc- 

 tion, the posterior part or " hinged" plate forming the "shield. ' ,.,, 



t The only other American Falconidie, having a similar nostril, are Milvago, PkaUobimas, 

 and perhaps a few other genera, belonging to, or generally placed with, the I Olybi 

 they also have the tooth, notch, etc., of the bill decidedly indicated; other characters, 

 however separate them verv widely from the Falconina . 



J /6ycr Xne forms an exception; but the other characters of this genus are eminently 

 Polyborinx. 



1870.J 



