606 



BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



tip, the extremity of this grayish portion obtusely wedge-shaped and 

 fading into white at the apex; sixth primary without any distinct 

 black area on inner web, which is white for about 45.5 mm. from tip 

 (measured along shaft), the outer web white for about 15.5 mm., then 

 slaty black for about 18 mm. (measured along edge), the anterior 

 outline of the black deeply concave and partially inclosing a grayish 

 white space; bill deep yeUow, paler at tip, the mandible with a subter- 

 minal lateral spot of red; rictus yellowish flesh-color; iris naples 

 yellow or yellowish cream color; bare orbital ring purplish gray 

 (in life) ; legs and feet pinkish flesh color (in life). 



Adults in winter. — Similar to summer adults, but head and neck 

 (especially pileum and hindneck) streaked with dusky. 



Young. — "Clove-brown, with darker streaks on the head and neck^ 

 dark centers and buffish-white margins to the feathers of the mantle; 

 rectrices nearly uniform brown, with very little marbling at the bases 

 and on the outermost; primaries brown, paler on their inner webs; 

 edge of wing and coverts almost unmottled grayish brown; under 

 surface brown, the tail-coverts striated; bill dark horn-color, paler 

 at the base; tarsi and toes reddish brown."" 



Adult male.— -Wing, 445-470 (458.6); tail, 179-196 (189.2); ex- 

 posed culmen, 59-65.5 (61.9); tarsus, 64-72 (68.7); middle toe, 62- 

 65.5 (64).^ 



Adult female. — ^Wing, 436; tail, 182; exposed culmen, 54; tarsus,. 

 59; middle toe, 55.5.'^ 



Coasts and islands of eastern Siberia and Kamchatka and Okotsk 

 Sea, breeding from eastern Siberia (Plover Bay; coast near Bering 

 Strait; Gichiga) to Kuril Islands; migrating southward to northern 

 Japan (Hakodate; Sakhalin Island; Samushi Island, and mouth of 

 Amur River; casual or occasional in Alaska (Chernoffsky Bay,. 

 Unalaska, large flock, Oct. 1, 1880; Port Clarence; Sitka), on Diomede' 

 Islands in Bering Strait (Sept., 1880), and on Herald Island, Arctic 

 Ocean; accidental at Franklin Bay, Mackenzie (June 9, 1901). 



Larus argcntatus (not of Pontoppidan, 1763) Middendorff, Reis. Sibil-., Zool., 

 1851, 243, part (Okhotsk Seaj. — Kittlitz, Denkw. Reis., ii, 1858, 225, part. 



a Saunders, Cat. Birds Brit. Mus., xxv, 1896, 259, 260. 



b Five specimens. 



c One specimen (Kuril Islands, June). 



