494 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



white on under and lateral portions of head, the under tail-coverts, 

 axillars, and under wing-coverts 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 rec trices 

 (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 itseK 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; ms 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.— Up^per parts pale grayish buff or light brownish 

 buff (dull avellaneous) , irregularly spotted or marbled with blackish, 

 except on forehead; under parts immaculate white or buft'y white, 

 the throat more or less suffused with sooty, sometimes uniform 

 sooty. 



Adult male.—Wmg, 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 Keewatin, 

 southern Ungava, and Newfoundland southward to coast of North 



o Fifteen specimens. b Seventeen specimens. 



