BIRDS OF PREY. EAGRES. 307 
as a distinct type. The above foui subgenera are all 
that we can admit into the accipitrine circle ; and it 
consequently follows that there still remains another to 
be determined by future observation or discovery : this, 
according to our theory, will be the tenuirostral type, 
which in the present instance must alike represent 
Aviceda and Cymindis ; in other words, it must be a kite 
among the hawks. Several of the birds arranged among 
the smaller eagles and the larger buzzards will probably 
be found, upon actual examination, more naturally allied 
to the aberrant hawks, especially such as Buteo borealis, 
pterocles, &c. 
(248.) The genus Ayuila is the first of those com- 
posing the aberrant division of the family wherein the 
upper mandible of the bill shows little or no inchcation 
either of the acute tooth of the falcons, or the promi- 
nent but rounded lobe of the hawks. AVe have a 
perfect example of this shaped bill in the white-headed 
hawk, forming the type of the restricted subgenus 
Halicetus, and the bill of the osprey is nearly the same ; 
but as we approach the more typical eagles, the length 
of the bill is greater, the size of the body is aug- 
mented, and all indications of the accipitrine structure 
are lost. These circumstances deserve attention, because 
they afford a strong ground for considering the true 
fishing eagles (Pandion) as a prominent, although an 
aberrant, type in the aquiline circle ; a station which 
still further confirms that which we have given to Ha- 
licetus. The typical eagles appear to arrange them- 
selves, as M. Cuvier has intimated, under two leading 
groups or subgenera, chiefly distinguished by the struc- 
ture of their wings. To those whose wings, like the 
golden eagle, are more or less lengthened, we l estrict 
the subgenus Acjuila, more for the sake of not creating 
a change of nomenclature among the best known species, 
than from any belief that they are the pre-eminent 
types of the aquiline group. The legs of these birds 
are all more or less plumed ; and in one species, the 
wedge-tailed eagle of New Holland (A. fucosa, Cuv., 
