BIRDS OF NORTH AND MIDDLE AMERICA 65 



swallowlike kites (genera Elanoides, etc.), or between the short-legged 

 strictly insessorial types and such long-legged forms as Geranospizias 

 seems a very wide one indeed, but when the forms of other faunas are 

 examined, it is found that these apparent gaps are so nearly bridged 

 that the subdivision of the family into trenchantly defined minor 

 groups presents real difficulty. 



SUPERFICIAL KEY TO THE AMERICAN SUBFAMILIES OF ACCIPITRIDAE 



a. Claws not grooved beneath, but smoothly flattened or even rounded. 



Elaninae (p. 67) 

 aa. Claws grooved beneath, 



b. Sides of head very densely feathered close up to the eyelids; the eyes not 

 overhung by a naked superciliary shield formed by the projecting edge 



of the superciliary process of the lachrymal Peminae (p. 80) 



66. Sides of head in proximity to the eyes less densely feathered; the eyes over- 

 hung by a naked superciliary shield. 



c. Feathers of the face forming a distinct ruff Circinae (p. 498) 



cc. Feathers of face not forming a ruff. 



d. Basal joint of second toe permanently ankylosed with the joint next 



beyond it; size moderate, never very large Milvinae (p. 113) 



dd. Basal joint of second toe not ankylosed with the joint next beyond it, 

 or, if so ankylosed (Haliaetus) size very large. 



e. Tail nearly as long as wing Accipitrinae (p. 140) 



ee. Tail much shorter than wing Buteoninae (p, 210) 



KEY TO THE NORTH AND MIDDLE AMERICAN GENERA OF ACCIPITRIDAE 



a. Claws not grooved beneath but smoothly flattened or even rounded. 



6. Size small, wings under 170 mm Gampsonyx (p. 76) 



66. Size larger, wings usually over 300 mm Elanus (p. 69) 



aa. Claws grooved beneath. 



6. Sides of the head very densely feathered close up to the eyelids; the eyes 



not overhung by a naked superciliary "shield" formed by the projecting 



edge of the superciliary process. 



c. Tail excessively forked, about as long as the long and narrow wing; cere 



not tumid, the nostril broadly ovate, without overhanging membrane. 



Elanoides (p. 82) 

 cc. Tail truncate or rounded, much shorter than the rather short and very 

 broad wing; cere tumid, the nostril slitlike, overhung by a soft mem- 

 brane. 

 d. Bill greatly hooked and much compressed; feathers of pileum soft and 

 blended, without tendency to greater elongation on the occiput; 

 lores naked, crossed by a narrow line of minute bristlelike feathers 



from anterior angle of eye to forehead Chondrohierax (p. 100) 



dd. Bill only moderately hooked and not greatly compressed; feathers of 

 pileum firm, distinctly defined, with tendency to elogation on the 

 occiput, where forming a more or less distinct narrow, pointed crest; 



lores more or less densely feathered Leptodon (p. 93) 



66. Sides of the head in proximity to the eyes less densely feathered; the eyes 

 overhung by a naked superciliary shield. 



