BIRDS TROCHILIDAE SEL A SPHORUS. 
133 
TROCHILUS ALEXANDRI, Bourc. & Mulsant. 
• Black-chinned Humming Bird. 
Trochilus alexandri, Bourcier k Mulsant, Ann. de la Soc. d'Agric. de Lyons, IX, 1846, 330.— Heermann, Jour. A. 
N. Sc. Phila. 2d ser. II, 1853, 269.— Cassin, 111. N. Am. Birds, I, v, 1854, 141 ; pi. xxii.— Gould, 
Mon. Trochilidae, xiv, Sep. 1857. Plate. 
g P> Q H . — Very similar to Trochilus c&lubris. Tail slightly forked; the chin and upper part of the throat opaque velvety 
black, without metallic reflections, which are confined to the posterior border of the gorget, and are violet, changing to steel 
blue or green, instead of coppery red. 
Female without the metallic scales ; the tail feathers tipped with white ; the tail graduated, not emarginat d ; the innermost 
feather among the longest. Length of male 3.30 ; wing 1.70 ; tail 1.26 ; bill .75. 
Hob. — Coast of California, southward. 
This species is very similar in color to trie common ruby-throated humming bird of the 
eastern United States, and represents it on the west coast. The upper parts and sides are of the 
same metallic golden green, the gorget of much the same extent, bordered behind by whitish, 
which (less pure) extends alon^ the middle of the belly, and involving the crissum, the feathers 
of which are greenish in the cei.tre. There is the same white spot behind the eye. T. alexandri 
is, however, rather the larger oi the two ; the bill nearly one-tenth of an inch longer. The tail 
is much less deeply forked, in fuct the outer feather is a little shorter than the second, and the 
innermost broad green one only about .10 of an inch shorter than the longest, instead of 
about .30. There is a tinge of metallic green to the tips of the tail feathers much less distinct 
in T. colubris. The whitish collar behind the metallic feathers of the throat, usually considered 
as a specific character, I find to be shared almost equally well by T. colubris. The chief distinc- 
tions between the two species are to be found in the violet steel blue or steel green reflections of 
the hinder part of the gorget, varying with the situation of the feathers and the specimen, as 
distinguished from the bright fiery or coppery red of the other. The chin and upper part of 
the throat extending beneath the eyes are opaque velvety or greenish black, without metallic 
lustre, while in T. colubris it is only the extreme chin which is thus dull in appearance. 
It is exceedingly difficult to distinguish the female of this species from that of T. colubris. 
The size is rather larger, and the tail rounded, without any emargination ; the middle feathers 
being .15 of an inch longer than the lateral ones, instead of actually shorter. The color is 
much the same. 
In both species the outer tail feathers, though broader than in the male, are quite acutely 
pointed on the terminal third, one side or the other of which is slightly concave, instead of 
being linear to near the end, and rounded without any concavity, as in Selasphorus and Atthis. 
The preceding description of this species is taken from specimens belonging to the very 
extensive collection of birds of the vicinity of Fort Tejon, made by Mr. John Xantus de Vesey. 
SELASPHORUS, Swain son. 
Selasphorus, Swainson, Faun. Bor. Amer. II, 1831. 
After separating the North American species usually called Selasphorus, with red metallic 
scales on the crown, and the outer primary not attenuated at the top, there remainbut two belong- 
ing to the restricted genus. Even in these there are some differences of form, but they may be 
considered in the present instance as specific characters. 
