544 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



Herpetotheres) ; spina intera sterni well developed; a prominent oval 

 gap between the first and second bronchial semirings; egg shells with 

 reddish yellow translucence. 



The Falconidae, as here defined, includes the true falcons, the 

 laughing falcons, pygmy falcons, forest falcons, and the caracaras. 

 As in the Accipitridae, we find here such extremes as the swift flying, 

 predacious duck hawks (genus Falco) and the rather sluggish scaven- 

 gerlike caracaras (genus Polyborus); from the tiny pygmy falcons 

 (subfamily Polihieracinae) to the sizable gyi-falcons (genus Falco). 

 The subfamily groups of [the Falconidae are, on [the whole, more 

 trenchantly characterized than are those of the Accipitridae. Like 

 the latter family, the former is cosmopolitan in range. 



KEY TO THE SUBFAMniES OF FALCONIDAE 



a. Xostril a small circular, or (in Polyborus) oblique-linear opening with bony 

 margin and ■with or without a central tubercle; wing long (always decidedly 

 longer than tail), pointed or only moderately rounded (outermost primary 

 never shortest, usually much longer than innermost primary) ; posterior 

 margin of auricular region with feathers normal; dorsal portion of spinal 

 pteryla deeply divided, each branch dilated exteriorly, 

 b. Xostril with no tubercle or only a poorly developed one; tarsus sUghtly to 

 much longer than middle toe, almost entirely unfeathered. 



Poliiiieracinae (extrahmital)" 



66. Nostril with a well-developed tubercle; tarsus hardly as long as, or shorter 



than, the middle toe, and feathered in its upper portion. 



c. HaUux abbreviated (much shorter than lateral toes) ; tarsi covered with 



smooth, variouslj' formed scales, the acrotarsium with a greater or lesser 



number of transverse scutellae; metasternum nearly truncated, entire 



or with a pair of oval foramina or else (in Polyborinae) very uneven, 



with two deep notches; eggshells with reddish yellow translucence. 



d. Maxillary tomium with a prominent toothlike subterminal process and 



mandibular tomium with a corresponding notch; superciUary process of 



lachrymal elongated, narrow, extending nearly across orbit; posterior 



margin of metasternum entire, preceded by a pair of oval foramina; 



foramen supracoracoideum absent; spina interna sterni distinct, 



spiny; anterior angle of carina sterni projecting forward as far as 



level of spina externa; one or two (only) outer primaries emarginated 



much beyond middle portion of inner web Falconinae (p. 612) 



dd. Maxillary tooth and mandibular notch indistinct or obsolete; super- 

 ciUary process of lachrymal short, extending not more than halfway 

 across orbit; posterior margin of metasternum deeply indented by a 

 pair of notches; foramen supracoracoideum present; spina interna 

 sterni indistinct, shelflike; anterior angle of carina sterni not pro- 

 jecting forward as far as level of spina externa; three or more outer 



" Polihieracinae Peters, Check-List Birds of World, i, 1931, 281 (includes Gamp- 

 sonyx, which is considered a genus of Accipitridae (Elaninae) in the present 

 work). 



