CIRCUS. 211 



Suborders. 



a 1 . Claws less curved, that of middle toe describing much less than a semicircle; 



outer toe not reversible Accipitres (p. 211) 



a 2 . Claws greatly curved, that of middle toe describing a full semicircle; outer toe 



reversible .....: Pandiones (p. 244) 



Suborder ACCIPITRES. 



This suborder includes all the hawks and eagles except the fish hawks 

 of the genera Pandion and Polioaetus; its members are distinguished by 

 having the outer toe not reversible and all of the claws moderately curved, 

 that of middle toe describing much less than a semicircle; concave or 

 under side of each claw hollowed or grooved instead of rounded. 



Family FALCONIME. 



Characters same as those given for the Suborder. 



Subfamilies. 



a 1 . Tarsus and toes longer and more slender Accipitrinae (p. 211) 



a 2 . Tarsus and toes shorter and stouter Aquilinae (p. 222) 



Subfamily ACCIPITRIN./E. 



In external characters this subfamily differs very little from Aquilince; 

 its members are weaker with body and legs more slender, wings and tail 

 longer, and plumage less compact. 



Genera. 



a 1 . Hinder aspect of tarsus with many hexagonal scales; wing, 300 mm. or more. 



Circus (p. 211) 

 a 2 . Hinder aspect of tarsus without hexagonal scales ; wing, 200 mm. or less. 



6 1 . Middle toe without claw about twice the culmen from anterior margin of cere. 



Astur (p. 216) 



6 2 . Middle toe without claw more than twice the culmen from anterior margin 



of cere Accipitcr (p. 219) 



Genus CIRCUS Lacepede, 1799. 



Bill moderate or weak, somewhat compressed; margin of upper man- 

 dible slightly sinuate but not toothed; wing very long and pointed, first 

 primary short, about equal to sixth; secondaries much shorter than 

 primaries; tail long, slightly graduated or nearly square; tarsus long 

 and slender, feathered at the base and overhung for about half its length 

 by the long thigh-feathers; front of tarsus with transverse plates, sides 

 and most of the hinder aspect with hexagonal scales; toes long, nails 

 long and much curved ; behind ear-coverts and sometimes across the throat 

 a "ruff" of short, rather stiff feathers, most conspicuous in the young 

 of melanoleucos and not very evident in the other species. 



