LINNEAN GENUS FALCQ. 



603 



The third variety, is the White-headed Falcon ; f • 



J ' ^ leucoce- 



Falco leucocephalus, Briss. phaius. 



I have never had an opportunity of examining 

 any falcon which corresponds with the descrip- 

 tion given of this bird. It cannot be consider- 

 ed, like most of the others, as forming a link 

 in the gradations of plumage from the yearling 

 Falcon to the adult Peregrine. In contradis- 

 tinction, therefore, to such as present the regu- 



B ECKSTEIN says ill regard to the F. famous , that he at one 

 time agreed with Buffon in considering it as a variety of F. 

 huteo, but >vas induced, from the observations of Becker, and 

 those of sportsmen, to consider it as a distinct species. In this 

 opinion, he was probably confirmed by his beHef that the Pere- 

 grine Falcon may in every stage of its plumage be distinguished 

 by the dark feathers on the side of the head. 



I have, however, good reason for believing, that that dis- 

 tinction, particularly in immature females, cannot always be re- 

 lied upon, and should therefore be unwilling to constitute the 

 F. C communis J fuscus a separate species, unless it can be shewn 

 from other causes than the occurrence of an individual wanting 

 some of those characters which usually distinguish the Pere- 

 grine Falcon, that they are really distinct. 



At all events, I would rather incline to the opinion of Buf- 

 fon and CuviER, that it is referable to the F. buteo, which 

 would be more in the spirit of Beckstein's own opinion re- 

 garding the F. communis, Gm. to which the F. fuscus appears tp 



nearly allied. 



