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U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
Tail strongly cuneate, the middle feather much longest and very hroad ; the outer very 
narrow, one-fifth the width of the middle. Body chiefly cinnamon colored ; throat feathers a 
coppery red ; top of head, and an occasional gloss on the hack, green......... .S. rufus. 
Tail rounded ; the middle feather a little shorter than the next one ; the outer rather broad, 
more than one-half the width of the middle one. Above, and on the sides below, green. 
Throat feathers purple. Edges of some tail feathers cinnamon brown... S. platycercus. 
SELASPHORUS RUFUS, Swain son. 
Red-backed Humming Bird. 
Trochilus rvfus, Gmelin, Syst. Nat. I, 1788, 497.— Aud. Orn. Biog. IV, 1838, 555 ; pi. 372. 
Selasphorus rufus, Swainson, F. Bor. Am. II, 1831, 324.— Ib. Aud. Birds Am. IV, 1842, 200 ; pi. 254. 
? Trochilus ruber, L.— Orn, I, 1788, 499. (Fide Bonaparte.) 
Trochilus collaris, Lath. (Bonaparte.) 
Trochilus sitkensis, Rathke. (Bonapaite.) 
Ornysmia sasin, Lesson. (Bonaparte.) 
Sp. Ch.—T ail strongly cuneate and wedge-shaped. Upper parts, lower tail coverts, and breast cinnamon. A trace of 
metallic green on the crown, which sometimes extends over the back ; never on the belly. Throat coppery red, with a well 
developed ruff of the same ; below this a white collar. Tail feathers cinnamon, edged or streaked at the end with purplish brown. 
Female with the rufous of the back covered or replaced with green ; less cinnamon on the breast. Traces only of metallic 
feathers on the throat. Tail rufous, banded with black and tipped with white ; middle feathers glossed with green at the end. 
Tail still cuneate. Length of male, 3.50 ; wing, 1.55 ; tail, 1.30. 
Hab. —West coast of North America, and across from Gulf of California to the Upper Rio Grande Valley. 
This species is about the size of the common ruby-throated humming bird, which it resembles 
also in many respects. The hill is rather narrower. The wings are long and falcate ; the two 
first primaries elongated and acutely lanceolate, but not attenuated as abruptly as in platycercus; 
the third is also acute. In most of the other species the first quill is much more linear than the 
second, and less acute than in this. 
The tail is strongly cuneate ; the outer feather .40 of an inch shorter than the middle, which 
projects .14 of an inch beyond the rest. The outer feather is very narrow, not exceeding .11 of 
an inch in width ; the rest widen and lengthen rapidly to the central one, which is very broad, 
(.35 of an inch ;) the central feathers are all ovate acuminate. 
In the female the primaries are less acutely falcate than in the male. The tail also, though 
cuneate, is less acutely so than in the male; the outer feathers broader and less acutely pointed. 
In the male, in its highest plumage, the entire upper parts, excepting the crown and the wing, 
(but including the tail,) the sides of the body under the wings, and a broad band across the 
breast and abdomen, with the lower wing coverts, cinnamon brown, rather paler beneath. The 
crown is obscurely golden green, not well defined. The entire throat, including a short ruff on 
the side of the neck, (about .40 of an inch long,) is metallic red, of the same shade as in the 
ruby-throat, although with brassy reflections in some lights. The sides of the neck beneath the 
ruff, the upper part of the breast, the anal region, and a small spot behind the eye are dull 
white. The wings are violaceous brown, their coverts metallic green. The tail feathers are 
cinnamon, with the outer webs near the tips violaceous brown ; this gradually becoming central 
instead of on the outer side. 
In some specimens, probably immature, the back shows spots of metallic green, while in 
others (as 6059) it is entirely covered with this color, except on the tail. 
The female is entirely of a metallic green above, with, however, more or less of a cinnamon 
