378 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
hallux slightly shorter. Wing three times as long as exposed culmen, 
the outermost primary longest. Tail more than half as long as wing, 
truncated or slightly double-rounded, all the rectrices very broad, 
rounded at tip. 
Coloration.—Above metallic bronze-green, including middle rec- 
trices, the other rectrices blackish or chestnut. Adult males with 
forehead and chin metallic violet-blue or velvety black, a black 
auricular stripe and white postocular stripe, the throat brilliant 
metallic green; adult females with the forehead sooty grayish brown, 
chin and other under parts dull whitish or buffy, the throat some- 
times spotted with green; auricular stripe grayish brown or dusky 
instead of black. 
Range—Mexico (including Lower California) to Nicaragua. (Two 
species.) 
KEY TO THE SPECIES AND SUBSPECIES OF BASILINNA. 
a. Lateral rectrices blackish (tipped with grayish in female); center of abdomen 
white. (Bastlinna leucolis.) 
b. Bill larger (exposed culmen 14.5-18.5); green of throat more extended poste- 
riorly, and white of abdomen more restricted. (Southern Mexico to Guate- 
mala.)..-....--..---.--...----Basilinna leucotis leucotis, adult male (p. 378). 
bb. Bill smaller (exposed culmen 14.5-15); green of throat more restricted poste- 
riorly and white of abdomen more extended. (Northern Nicaragua.) 
Basilinna leucotis pygmza, adult male (p. 381). 
aa, Lateral rectrices chestnut or cinnamon-rufous: abdomen light cinnamon-rufous or 
buffy cinnamon. (Cape San Lucas district, Lower California.) 
Basilinna xantusi (p. 382). 
BASILINNA LEUCOTIS LEUCOTIS (Vieillot). 
WHITE-EARED HUMMING BIRD. 
Adult male —Forehead, loral and malar regions, chin, and upper 
throat rich metallic violet or violet-blue, passing into velvety black 
on suborbital and auricular regions, and into duller black, faintly 
glossed with bluish or greenish, on crown; occiput and hindneck dark 
metallic bronze or bronze-green; back, scapulars, wing-coverts, and 
rump varying from bright metallic green to bronze-green or golden 
green, the upper tail-coverts similar but usually more bronzy (some- 
times golden bronze), and, together with feathers of ramp, more or 
less distinctly margined with rusty; middle pair of rectrices bright 
bronze-green, bronze, or golden bronze, the next pair similar but 
darker, the remaining rectrices bronzy black, tipped (more or less 
distinctly) with bright bronze or bronze-green; remiges purplish 
dusky, the inner secondaries glossed with bronze-green; a broad 
white postocular stripe, extending backward and downward above 
and behind upper margin of auricular region to side of neck; middle 
and lower throat brilliant metallic emerald green (more yellowish 
green posteriorly) abruptly defined against the dark violet or violet- 
