12 



SUB-FAMILY. 



POLYBOnOIDINM or GYMNOGENES. 

 Genus POLYBOEOIDES fSmitJi.J 



GYMNOGENYS (Lesson.) 

 POLYBOEOIDES EADIATUS (Scopoli ) 



RADIATED GYMNOGENE. 



In the instance of the Gymnogenes, it seems necessary 

 to treat a single genus as forming of itself alone a separate 

 sub-family, a distinction which, even if it rested on no 

 other foundation, might, perhaps, in this case, be suffi- 

 ciently justified by one peculiarity wTiieh occiu's in this 

 species, and in no other bird with which I am acquainted — 

 viz., the singular flexibility of the joint connecting the tibia 

 and tarsus, which permits the latter bone to be thrown back- 

 ward to such an extent as to give to the joint the appear- 

 ance of being inverted by the position in which the tarsus is 

 thus placed. The general character of the form and plumage 

 of this bird, its general habits as far as they are known, 

 and also the bare space which it exhibits between the e^e 

 and the bill, show a decided affinity between it and the 

 Secretary. On the other hand it also bears, both in adult 

 and immatm'e plumage, considerable resemblance to some of 

 the Accipitrinaj, especially to a hawk of tropical America, 

 the Isehnosceles gracilis, and to the larger species of the 

 African genus Melierax. The Eadiated Gymnogene inhabits 

 the Aft'ican contment, where it has an extensive geogra- 

 phical range. In Western Africa it has been observed to 

 extend as far northwards as the Gambia, and southwards 

 as the Gaboon, and to occur in several intermediate local- 



