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and tipped with white ; wings reaching to the second band ; 
second quill much shorter than the sixth ; third than the fifth. 
Length about one foot. 
Adult, slate-color, beneath white, barred with ferruginous. 
Young, dark brown, skirted with ferruginous ; beneath 
white, with oblong ferruginous spots. 
Falco pensylvanicus, and Falco velox , Wilson . Falco 
dubius , Gm. Lath. Dubious Falcon , Penn . Arct. Zool. 
Lath. Syn. Falco fuscus, (Miller. III. pi. is?) Gm. Lath . 
American Brown Hawk , Lath. Syn. 
Note 2. Falco borealis. It will be proper to remark, that this 
species is almost as much an Astur of the first section as a Buteo. 
Falco hyemalis on the contrary, is decidedly a typical Buteo : the 
very young of these two species are so similar, that they can only 
be distinguished by the slight differences of the bill and claws, and 
by the length of the primaries, the fourth being the longest in F. 
borealis , while it is the fifth in F. hyemalis. To one or other of 
these species, in their various states, most probably to the former, 
must be referred Buteo ferruginicaudus , B. fuscus , and B. galli- 
nivorus , of Vieill. Ois. d' Amerique. This conjecture is founded 
on the examination of a fine series of specimens, of Falco borealis 
in my collection, of all ages, and exhibiting all the gradations of 
color. The changes of F. hyemalis are not yet satisfactorily ex- 
plained, and we would direct the attention of American Ornitholo- 
gists to the subject. 
The Broad-winged Hawk of Wilson, Falco pensylvanicus , of 
which we lately examined several specimens, is erroneously referred 
to Astur ; it is a typical Buteo. The young wants the white on 
the tail, that part being obsoletely banded with black and dusky, 
the inferior parts are pure 'white, with rare blackish oblanceolate 
spots. It may at once be known from the two other Buteones , by 
its much smaller size, and wider, though more obscure tail-bands. 
The female is, however, even more than is usual, larger than the 
male. The adult is clouded beneath ; tail barred with white. 
Falco melanopterus. We are now of opinion, that the bird 
described by us under this name, is a distinct species peculiar to 
America, and may be characterised as follows. 
