BIKDS OF NORTH AND MIDDLE AMERICA. 



585 



wing-coverts, immaculate pure white; back, scapulars, and wings 

 uniform pale gull gray, on the primaries passing gradually into white 

 terminally, the secondaries passing into white terminally (for about 

 44.5 mm.); shafts of primaries yellowish white to pale straw yellow; 

 bill yellow (lemon, or gamboge), the mandible with a lateral sub- 

 terminal spot of red; iris yellow; naked eye-ring red; legs and feet 

 flesh color or pinkish (in life). 



Adults in winter. — Similar to the summer plumage, but h(\ad and 

 neck streaked or clouded with pale-grayish brown or brownish gray ; 

 naked eye-ring pale yellow and legs and feet paler flesh color. 



Young in first plmnage. — G(>neral color grayish white, more or 

 less tinged with pale brownish gray, or grayish brown, on under parts, 

 the upper parts transversely mottled with brownish gray and more or 

 less tinged with pale buffy, the head and neck streaked and clouded 

 with pale brownish gray or grayish brown; tail pale brownish gray 

 or grayish brown, more or less mottled with whitish; bill yellowish 

 or flesh color with terminal portion blackish; iris yclloA\'ish brown; 

 legs and feet brownish flesh color. 



/wmafwre (second winter?). — Entirely white or yellowish white, 

 the bill and feet colored essentially as in first plumage. 



Downy young. — Grayish white, the under parts more purely white ; 

 head and neck irregularly marked with scattered large spots of dusky, 

 the back, wings, and rump irrc^gularly clouded with dark grayish. 



Adult male. —\\nng, 428-474 (453.7) ; tail, 175-207 (186.3); ex- 

 posed culmen, 53-67.3 (60.2); tarsus, 53.1-74 (65.6) ; middle toe, 

 51.3-66 (61.3). « 



Adult female.— ^mg, 424-457 (436.7); tail, 172.5-190 (182.7); 

 exposed culmen, 49-60.5 (55.4); tarsus, 57-69.3 (62.5); middle toe, 

 53-63 (56.5).^' 



« Eleven specimens. 



& Eight specimens. 



Locality 



MALES. 



Three adult males from northeastern North America 



Four adult males from Point Barrow, Alaska 



Four adult males from Bering Sea, etc., Alaska 



FEMALES. 



One adult female from Spitzbergcn 



Two adult females from Cumberland Gulf 



Two adult females from Point Barrow, Alaska 



Three adult females from St. Michaels and Point Gustavus, 

 Alaska 



Middle 

 toe. 



59.8 

 61.6 

 62.3 



63 



(58.5) 

 53.2 



55.9 



