62 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



more than half as long as fourth toe; femorocaudal muscle present, accessory 

 femorocaudal muscle absent; myological formula A4-. 



b. Palate indirectly desmognathous or (in genus Elanus) schizognathous ; 

 vomer not expanded anteriorly, not closely applied to maxillopalatines ; 

 lachrymal usually provided with a superciliary plate (absent in Pandioni- 

 dac, Perninae, and Aegypiinae) ; antorbital plate (prefrontal) often 

 much reduced, generally tongue-shaped, articulating or even fused by 

 its free end with distal extremity of lachrymal; squamosal prominence 

 not strongly developed; ventral surface of maxilla without median 

 bony ridge; mandible without ramal vacuity; nasal bones very incom- 

 pletely ossified, the nostril with a more or less oval or pyriform, usually 

 large, opening, fully exposing the nasal septum, without central bony 

 tubercle, or if slitlike, the lower end the posterior one, and if small 

 and approximately circular without bony rim or central tubercle; pro- 

 coracoid small, articulating with scapula only, and widely separated 

 from clavicle; thoracic vertebrae all free; spina interna sterni absent; 

 no gap between first and second bronchial semirings; egg shells with 

 green translucence. 

 c. Tarsus very stout, covered with small, rough, somewhat imbricated 

 projecting scales; under surface of toes covered with prominent 

 spicules; the outer toe reversible; claws of all the toes long, very 

 strongly curved, of equal length, and contracted and rounded on the 

 under surface; lachrymal with no superciliary plate; coracoids over- 

 lapping at sternum; upper portion of tarsometatarsus wdth a bony 

 ring, through which passes the common tendons of the toes; tendons 



of biceps split for nearly entire length; caeca large Pandionidae 



(p. 523) 

 cc. Tarsus slender, covered with smooth scales; under surface of toes 

 without spicules; the outer toe fixed; the claws graduated in size from 

 that of the hallux (largest) to that of the outer (fourth) toe (smallest), 

 not contracted to their under surface where (except in Elaninae) 

 broadly grooved or concave (in transverse section) ; lachrymal usually 

 with a superciliary plate (absent in Perninae and Aegypiinae); 

 coracoids not overlapping at sternum; upper portion of tarsometa- 

 tarsus without bony ring; caeca small; tendons of biceps not split. 



Accipitridae (p. 63) 

 hb. Palate directly desmognathous; vomer expanded anteriorly, closely applied 

 to maxillopalatine process; lachrymal without superciliary plate; 

 antorbital plate (prefrontal) largely developed, the outer border closely 

 applied to or fusing with the lachrymal ; squamosal prominence strongly 

 developed; ventral surface of maxilla w^th a median bony ridge; 

 mandible with ramal vacuity; nasal bones almost completely ossified, 

 the nostril with a very small circular or slitlike aperture with a con- 

 spicuous central bony tubercle or else (in genus Micrastur) large, 

 broadly oval and without any long rim or obvious central tubercle; 

 procoracoid large, articulating with the clavicle; thoracic vertebrae 

 (except the penultimate) ankylosed (except in Herpetotheres) ; spina 

 interna sterni well developed; a prominent oval gap between first and 

 second bronchial semirings; egg shells with reddish yellow translucence. 



Falconidae (p. 543) 



