S18 Mr. Vigors's Sketches in Ornithology. 



the question which is most consonant to his peculiar views, and 

 which best accords with the predominance of those characters on 

 which he chiefly depends for distinction between his groups. 

 Founding thus the line of demarcation between the Vulturidm and 

 the Falconidce on the nakedness of the head and cheeks, M. 

 Vieillot has united all the birds of which I speak with the former 

 family : while M. Cuvier, on the other hand, has left them among 

 the latter, forming his decision chiefly on their general appearance 

 and habits. In the present state of the question I feel no hesita- 

 tion in agreeing with M. Cuvier, and in retaining these birds in 

 their original station, until at least more decided information than 

 we can as yet obtain of them, enables us to speak with more confi- 

 dence. We are furnished with an additional reason for this deci- 

 sion in the circumstance of these birds possessing this nakedness 

 about the head in the adult state only; when young, their whole 

 head is covered with feathers.* This fact, which has been ascer- 

 tained to be the case at least in some species, evinces the gradual 

 manner in which nature deserts any particular character or mode 

 of formation. The birds before us thus pass without any abrupt- 

 ness into the Eagles,- the full characters of which they possess in 

 their earliest age. I shall adhere to the generick titles given to 

 them by M. Vieillot, who appears to have been the first to have 

 characterized them. 



The group of the Falconidce that seems nearest to the Vultures 

 is the genus 



Ibycter, Vieill. 



which is distinguished by the nakedness of its cheeks, throat, 

 and crop. To this character M. Vieillot has added those of its 

 bill being convex above ; its inferiour mandible notched near the 

 end, and somewhat pointed ; its cere smooth ; and its nails pointed 

 The type of the genus is the F. aquilinus, Gmel., the Petit Aigle 



* II est certain que dans les jeunes Caracaras noirs, comme dans les jeunes 

 du Chimachima, toute la tete est converte de plumes, et que le tour des yeux 

 est 1' unique partie qui soit nue. La nudite de la tete augmente avec l'age. 

 Temm. Art. Falco aterrimus, PI. Col. 37. 



