BIRDS OF NORTH AND MIDDLE AMERICA. 339 
in length, slightly shorter than middle toe, the hallux shorter 
than lateral toes. Wing, about three times as long as exposed cul- 
men, the ninth (next to outermost) primary longest. Tail about 
two-thirds as long as wing, in adult male forked and with the next 
to outermost pair of rectrices excessively elongated, in adult female 
double-rounded, with lateral rectrices shorter than middle pair. 
Adult males with a conspicuous crest on each side of occiput. 
Coloration.—Adult male with top and sides of head, including 
crests, together with tail, black; rest of plumage metallic green, 
brighter on under parts; adult female metallic green or bronze-green 
above (including middle rectrices), dull white beneath, spotted with 
green laterally. 
Range.—Island of Jamaica. (Two species.) 
KEY TO THE SPECIES OF AITHURUS. 
a. Bill with at least greater part of mandible pale brownish or yellowish (red or pink 
in life); adult male with under parts purer (less yellowish) green. (Southern 
slope of Jamaica.)....-..-.---------e- eee eee eee Aithurus polytmus (p. 339). 
a. Bill wholly black (in both sexes); adult male with under parts more yellowish 
green. (Northern slope of Jamaica.).......-..-- Aithurus scitulus (p. 341). 
AITHURUS POLYTMUS (Linnzus). 
STREAMER-TAILED HUMMING BIRD. 
Adult male.—Pileum dull black or blue-black; occiput and nuchal 
crest deep velvety black; back, scapulars, wing-coverts, rump, and 
upper tail-coverts bright metallic green, bronze-green, or greenish 
bronze; tail (including elongated rectrices) black, the middle pair of 
rectrices more or less strongly glossed with bronze-green or greenish 
bronze, the other rectrices sometimes similarly but less strongly 
glossed, at least basally; primaries dark brownish slate or dusky, 
glossed with purplish bronze; secondaries darker (nearly black), 
faintly glossed with violaceous, the innermost ones with outer web 
mostly metallic green or bronze-green; malar region, sides of neck, 
and under parts (except under tail-coverts) luminous metallic yel- 
lowish green (nearest apple green, but much purer in hue); under 
tail-coverts and under surface of tail blue-black or black faintly 
glossed with bluish; bill pale brownish or dull yellowish (pink or red 
in life), dusky at tip; iris dark brown; feet dusky; length (skins), 
including elongated rectrices, 211-256 (234); wing, 64.5-68.5 (66.4), 
tail (elongated second rectrix), 152-184 (167.5); middle rectrices 
28-32 (29.9); culmen, 20-21.5 (20.6).¢ 
Immature male.—Similar to the adult male, but without elongated 
rectrices; rectrices tipped with bronze-green or greenish bronze, and 
under tail-coverts strongly glossed with greenish bronze. 
« Ten specimens. 
