BIRDS OF NORTH AND MIDDLE AMERICA. 623 
CALYPTE COST (Bourcier). 
COSTA’S HUMMING BIRD. 
Adult male.—Head, except postocular region, very brilliant metallic 
violet or amethyst purple, changing to violet-blue or even greenish 
and more reddish purple (magenta) in certain lights, the latero- 
posterior feathers of throat much elongated; rest of upper parts, 
including four middle rectrices, rather dull metallic bronze-green or 
greenish bronze; tail (except four middle rectrices) grayish brown or 
brownish gray, faintly glossed with bronze-greenish, the rectrices darker 
on shafts and toward tip; remiges brownish slate or dusky, faintly 
glossed with purplish; foreneck very pale brownish gray or grayish 
white, passing into more decidedly grayish on chest and median 
line of breast and abdomen; rest of under parts metallic bronze- 
green or greenish bronze, the feathers more or less distinctly mar- 
gined with dull grayish; femoral tufts and conspicuous tuft on each 
side of rump white; under tail-coverts light brownish gray or bronzy 
centrally, margined with whitish; bill dull black; iris dark brown; 
feet dusky; length (skins), 77-90 (83); wing, 43-45.5 (44.4); tail, 
22-24.5 (22.6); middle rectrices, 17.5-20 (18.6); exposed culmen, 
16-19 (17.2).¢ 
Adult female.—Above rather dull metallic bronze-green or greenish 
bronze, much duller on pileum, where (at least on forehead) some- 
times dull grayish brown; middle pair of rectrices bronze-green, the 
next pair similar but with terminal portion black; third pair tipped 
with dull white or pale brownish gray, extensively black subter- 
minally and dull brownish gray basally, the gray and black separated 
(at least on outer web) by more or less of metallic bronze-green; 
fourth and outermost pairs with whitish tip broader, basal grayish 
more extended, and with little if any metallic greenish between the 
gray and black; remiges brownish slate or dusky, faintly glossed 
with purplish; under parts pale brownish gray, paler (dull whitish) 
on chin,- upper throat, and under tail-coverts; femoral tufts and 
tuft on each side of rump white; bill, etc., as in adult male; length 
(skins), 74-91 (81); wing, 43.5-46 (44.7); tail, 21.5-25.5 (23.6); 
culmen, 17-20 (18.2).® 
Young male.—Similar to the adult female but feathers of upper 
parts more or less distinctly margined with pale grayish buffy, tail 
double-rounded instead of rounded, and throat with a central patch 
of metallic purple or violet feathers (in older individuals similar 
feathers on crown also). 
Young female.—Similar to the adult female but feathers of upper 
parts margined with pale grayish buffy. 
4 Thirteen specimens. b Twelve specimens, 
