428 BIRDS OF ILLINOIS. 



Of the foregoing groups only two have representatives in North 

 America; the Falconer, with several members, and the Polyborece 

 with a single tropical species coming just within our border. 



The Falconea are represented in North America by apparently a 

 single genus, Falco, although it may ultimately prove necessary to 

 raise one or more of the supposed subgeneric divisions to full 

 generic rank. 



GENUS FALCO LINN^US. 



CHAB. Bill strong, Its breadth at the base eaual to or exceeding its length; upper 

 outline of the cere on a level with, or rather lower than, the base of the culmen; gonys 

 very convex, the chord of the curve about half that of the culmen. Maxillary tomium 

 with a very prominent "tooth," and mandibular tomium with a corresponding deep 

 notch; the end of the mandible being truncated and the tip of the maxilla compressed 

 and produced into a strongly hooked tip. Nostrils small, circular, and with a conspicuous 

 central bony tubercle. Orbital region bare; projecting superciliary shield bare and 

 conspicuous, though not very prominent. Tail shorter than the wing, more or less 

 rounded, the feathers rather hard. Primaries very strong, elongated, never more than 

 two having their inner webs emarginated, the emargination angular and near the end of 

 the quill. Tarsus never with a single continuous row of transverse scutellae, either in 

 front or behind. Middle toe very long never much shorter, and sometimes longer than 

 the tarsus. 



The above diagnosis includes the essential characters of all the 

 true Falcons, which apparently constitute a single genus, with, how- 

 ever, a number of more or less strongly marked subgeneric divisions. 

 What are probably distinct genera of Falconince are Spizapteryx, 

 KAUP (South America), and lerax VIGORS (Indian). The latter in- 

 cludes the smallest of the Accipitres, some species being no larger 

 than the European House Sparrow (Passer domesticus). 



The following groups of North American Falcons are pretty well 

 characterized, and some of them (especially Tinnunculus) may be 

 entitled to generic rank: 



A. Only the first primary with inner web emarginated. First or second quill longest, 

 the first longer than the fourth. Sexes essentially alike in coloration, but young 

 very different from adults. 



1. Hierofalco. Tarsus longer than middle toe, and feathered far below the knee. 

 First quill shorter than the third. Size large to largest of the family. 



2. Rhynchodon. Tarsus shorter than middle toe and scarcely feathered below the 

 knee. First quill equal to, or longer than, the third. Size large to medium. 



B. Two outer primaries with inner webs emarginated. Second or third quill longest, 



the first shorter than the fourth. 



a. Basal joint of toes without transverse scutollaa. Tarsus about equal to the mid- 

 dle toe. 



