296' ON HIE CLASSIFICATION OF BIRDS. 
to be natural; and it therefore follows, as a legitimate 
deduction, that as the insessorial order is circular, so 
also is the raptorial. 
(242.) In regard to the external affinities of the 
family, little need be said, since its situation between 
the vultures and the owls has been universally admitted 
since the days of Linna;us. The bearded vulture of 
the Alps, as already remarked (235.), is an eagle in its 
habits, food, and many parts of its structure : while 
several of the Aquila evince their affinity to the Vul- 
turidm by their partially naked heads, and by feeding 
occasionally upon carrion. Some of the buzzards, on 
the other side of the falconine circle, show the strongest 
possible affinity to the owls, by their large ears, often 
surrounded, as in Circus, by a ruff of stiff feathers — 
their hunting, like the rough-legged buzzards, by 
twilight — and by the soft lax plumage, seen more par- 
ticularly in the last-mentioned species. These external 
affinities, indeed, have been so long known to naturalists, 
that they would not have been here repeated, did not 
their admission confirm the analogical demonstration 
we have just given of the family ; for if this is correct, 
if follows, that, as the primary divisions of the Faleonidce 
represent the primary divisions of the perchers, they 
consequently represent those of aU the circular groups 
in the class of Aves. 
(243.) Upon entering more into the details of the five 
leading generic groups, we shall experience more dif- 
ficulty, from the causes we have already mentioned, than 
with almost any other group in the whole circle of 
ornithology. We have, for several years, assiduously 
collected, where procurable, all such specimens as were 
adapted, from their size, to a private museum, and have 
taken an extensive series of notes regarding such as 
were only to be seen in other collections; but these 
materials are still insufficient to allow of that complete 
exposition of all the newly proposed genera which it 
would have been so desirable in this place to furnish. 
Several of these, indeed, we know only from figures or 
