BIRDS—BUTEONINAE-BUTEO COOPERI. 
31 
quills and the bronzed or silky olive lustre of their inferior surfaces are quite remarkable. The 
exposed edges and ends of some of the secondaries in the present specimen have a distinct purple 
lustre. On examination and comparison with some black species from Mexico, we are not 
without a suspicion that the adult of this bird is of that color. 
The only specimen of this species is in the collection made by T. Charlton Henry, M. D., 
United States army, at Fort Fillmore, New Mexico, and is that which is represented in our plate. 
List of specimens. 
Catalogue No. 
Sex and age. 
Locality. 
When collected. 
Whence obtained. 
Original No. 
Collected by— 
Measurements. 
Length. 
Extent. 
Carpal 
joint. 
8550 
Fort Fillmore, N. M 
Dr. Henry_, _ 
Sub-Genus Tachytriorchis. 
BUTEO COOPERI, Cassin. 
Buteo Cooperi, Cassin, Proc. Acad. Philad. VIII, 253, (1856.) 
About the size of Buteo borealis, but belonging to the same group as Buteo erylhronotus of South America, (genus Tachytri¬ 
orchis, Kaup, as restricted by Bonaparte, Conspectus Avium, p. 17.) 
Bill strong; edges of upper mandible lobed ; wings long; quills very wide and strong, fourth quill longest; tail moderate ; 
legs rather long, tarsus feathered in front slightly below the joint, behind and remaining portion in front naked, with about 13 
transverse scales in front and 11 to 13 behind, the latter running into a circular or hexagonal form towards the joint with the 
tibia; claws long, rather slender, very sharp, and strongly curved. 
Tail white at its base ; external feathers, with their outer webs cinereous and their inner webs white, mottled with cinereous ; 
other feathers of the tail mottlefjand striped longitudinally with white, bright rufous, dark brown, and cinereous, darker on the 
outer web. The rufous color most conspicuous on the two middle feathers and on the outer webs of others. A subterminal 
transverse band of dark brown, tipped with reddish and white. 
Head above and neck behind having the feathers white at base, tipped and with longitudinal stripes of brownish black ; oack 
and rump brownish black tinged with cinereous ; upper tail coverts white, transversely barred with dark brown and tinged with 
rufous; wing coverts and quills brownish cinereous, lighter on the quills ; coverts with concealed spots of white at their bases ; 
inner webs of quills white, mottled, and irregularly banded with light ashy ; exposed ends of quills light, nearly white. Under 
parts white, with narrow stripes of dark brown on the throat, neck and flanks ; (breast, abdomen, and under tail coverts pure 
white.) A large spot of brownish black on the under wing coverts next to the upper edge of the wing; other under wing coverts 
white, with a few spots of dark brown. Tibial plumes tinged with reddish yellow. Bill dark bluish ; tarsi and toes yellow. 
Total length, about 21 j inches ; wing, 15 inches ; tail, 9 inches. 
This is the only species yet discovered within the limits of the United States which belongs to 
the group above indicated, the species of which, as restricted, are principally South American, 
and are, for the most part, of light colors, as in the present bird. The present bird may he easily 
distinguished from any other North American Buteo by its light colors. 
One specimen only is in the collection, and was obtained at Santa Clara, California, by J. G. 
Cooper, M. D. It is not in adult plumage, hut is very probably sufficiently mature to indicate 
the adult plumage, except the colors of the tail. The latter is quite remarkable and peculiar in 
its colors, which are disposed in irregular longitudinal stripes, as above described. 
This bird is one of the most interesting and valuable of the ornithological discoveries made by 
the exploring and surveying expeditions. It is well represented in the plate cited above, but 
necessarily the figure is much reduced, and is made from the only specimen that has ever come 
under our notice. 
