494 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
white on under and lateral portions of head, the under tail-coverts, 
axillars, and under wing-coyerts pure white; outer web of outermost 
rectrix gray, becoming darker terminally, in abrupt contrast with 
the pure white of inner web, the outer webs of remaining rectrices 
(except middle pair) pale gray; outer web of outermost primary 
blackish slate, of the other primaries pale silvery gray; inner webs 
of distal primaries for the most part white but with a stripe of 
grayish next to shaft, this stripe abruptly defined on outer five quills 
but becoming gradually broader and paler toward the fifth, and 
extending round tip of web and returning toward base as a sub- 
edging, the edge itself white; five inner (proximal) primaries with 
inner webs pale silvery gray edged with white; bill vermilion red, 
blackish terminally, except on tomia; inside of mouth orange- 
vermilion; edges of eyelids black; iris dark brown; legs and feet 
orange-vermilion. 
Adults in winter.—Similar to summer adults, but forehead, crown, 
and anterior part of lores white, the crown intermixed with black; 
only the occiput and nape uniform black; under parts pure white. 
Young.—Orbital region, occiput, and nape black; crown mixed 
black and grayish white; forehead, loral region, sides of head (below 
orbital region), entire under parts, upper tail-coverts, inner webs of 
rectrices, and tips of secondaries, white; upper parts (except as de- 
scribed) pale gray, the scapulars, interscapulars, and tertials tipped 
with pale buff and marked with a subterminal lunule of dusky brown 
or grayish brown; anterior lesser wing-coverts dusky, forming a 
broad bar across anterior portion of wing; primaries much as in 
adults, but darker; larger wing-coverts pale gray, indistinctly mar- 
gined or edged with white; outer webs of rectrices grayish, much’ 
darker on outermost pair; bill dusky brownish, the mandible paler 
and more reddish basally; legs and feet pale yellowish in dried 
skins (flesh color in life ?). 
Downy young.—Upper parts pale grayish buff or light brownish 
buff (dull avellaneous), irregularly spotted or marbled with blackish, 
except on forehead; under parts immaculate white or buffy white, 
the throat more or less suffused with sooty, sometimes uniform 
sooty. 
Adult male.—Wing, 256-273 (265.6); tail, 128-174 (148.9); 
exposed culmen, 33-39 (37.2); tarsus, 18-20.5 (19.2); middle toe, 
16.5-18 (17.3).¢ 
Adult female—Wing, 235-273 (257.7); tail, 132.5-161.5 (147.4); 
exposed culmen, 32-40.5 (35.7); tarsus, 17.5-20 (18.9); middle toe, 
16-18 (17.1).° 
Breeding from Mackenzie (Great Slave Lake), central eawatha. 
southern Ungava, and Newfoundland southward to coast of North 
@ Fifteen specimens. > Seventeen specimens. 
