THE HUMMING BIRDS. 315 



chinned Humming Bird (T. alexandri) it is velvet-black for the upper 

 half and metallic violet, changing to blue, on the lower. In the Violet- 

 throated Humming Bird (T. violajngulum), a species so rare that but a 

 single specimen has be'en obtained, it is lilac-purple. 



We have now exhausted the list of North American Humming Birds, 

 the males of which are adorned with true gorgets, and have come to a 

 small group of species which are not only characterized by the absence 

 of this ornament (though the throat is brilliantly colored in them all) 

 but also by the form of the bill, which is much broader, with the nasal 

 valves wholly unfeathered and somewhat swollen, the color of the bill, 

 in life, being reddish (sometimes deep red) with a dusky tip, whereas 

 in all the other North American hummers the bill is entirely or mainly 

 black. Of this group there are three species known to cross the Mex- 

 ican boundary into the southern parts of Texas and Arizona, while an- 

 other is peculiar to Lower California. The latter is Xantus's Humming 

 Bird (Basilinna xantusi), the only known congener of which is the White- 

 eared Humming Bird (B. leucotis) of the Mexican highlands. The male 

 of Xantus's Humming Bird has the forehead dark blue, the chin and a 

 broad stripe beneath the eye velvety black, the throat and chest bril- 

 liant emerald green, and the tail chestnut. Behind the eye is a broad 

 white streak. Its Mexican relative is very similar, but differs in the 

 color of the tail, which is blackish with the middle feathers greenish 

 bronze, and in the forehead being much brighter blue. 



The Circe Humming Bird (lache latirostris) belongs to western Mex- 

 ico,but occurs just beyond the border in Arizona. The male is bronzy 

 green above, the under parts brilliant green, changing to sapphire-blue 

 on the throat, the under-tail coverts white. 



The remaining two species occur in the lower Rio Grande Valley of 

 Texas and belong to the genus Amazilia. They agree in being bronzy 

 green above, the tail rufous or chestnut (with feathers margined at tips 

 with bronzy), and in being brilliant green below, changing to brownish 

 or buffy posteriorly. Reiffer's Humming Bird (A. fuscicaudata) has the 

 belly and flanks brownish gray, under tail coverts deep cinnamon, and 

 upper tail coverts chestnut. The Buff-bellied Humming Bird (A. cer- 

 viniventris) differs in having the belly, flanks, and under tail coverts 

 pale cinnamon or buff, and the upper tail coverts chiefly green or 

 bronzy. 



The following " key " is intended to facilitate the identification of 

 genera merely, and excludes very numerous forms not found within the 

 geographical limits indicated above, though those of contiguous terri- 

 tory are included. The " key" is essentially the same as that on pages 

 303 to 309 of the author's " Manual of North American Birds" * modi- 

 fied, however, to better adapt it to the present work. 



* A Manual of North American Birds, by Robert Ridgway. Illustrated by 464 out- 

 line drawings of the generic characters. Philadelphia : J. B. Lippiucott Company, 

 1887. Royal octavo, pp. i-xi, 1-6;U, pll. i-cxxiv. Frontispiece (portrait of Prof. 

 Spencer F. Baird), and memorial leaf. 



