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APPENDIX 
To the “ Genera of North American Birds , and Synopsis 
of the Species found in the United States 
Note 1 . Faico velox. We have in another place quoted as 
doubtful synonymes of this species, Faico dubius, and Faico obscu- 
rus of authors, but have not restored to the species its old name, 
finding it next to impossible to arrive at any certainty relative to 
these meagre indications. Since this note was first written, how- 
ever, we have had sufficient proofs to warrant us in asserting that 
Faico obscurus is <c a young female” of F. columbarius ; and that 
Faico dubius is undoubtedly Wilson’s supposed new species. Faico 
fuscus of authors is another and still prior name for the same, and 
we shall therefore adopt it. 
We have also a new species to be added to the same section. 
These discoveries render it necessary to replace this part of the 
Synopsis with the following. 
13 bis. Falco cooperii, Nob. Tail rounded, with four black- 
ish bands, and tipped with white; wings reaching to the second 
band ; second quill subequal to the sixth, third to the fifth. 
Length eighteen inches or more. 
Adult unknown. Young dusky-brown, skirted with ferru- 
ginous ; beneath white, with oblanceolate dusky-brown spots. 
Cooper's Hawk, Faico cooperii, Nob. Am. Orn. ii. pi. io. 
fig- 1- young. 
Inhabits North America : appearing in autumn and the 
beginning of winter in the middle states. 
14. Falco fuscus, Gm. Tail even, with four blackish bands, 
