646 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



or dusky, the tip, narrowly, whitish; outermost primary with outer 

 web and a stripe on inner web next to shaft, together with terminal 

 portion, black, the remaining portion white; second and third pri- 

 maries (from outside) similar, but the white more and more restricted; 

 fourth primary grayish white on both webs, the subterminal portion 

 black for more than 25 mm.), the tip white; remaining (proximal 

 primaries pale neutral gray; bill dusky; legs and feet pale brownish 

 (in dried skins) . 



Immature (young in first winter ?) . — Similar to winter adults but 

 central lesser wing-coverts dusky, tail with a subterminal band of 

 dusky, and primaries as in first plumage. 



Adult 7mZe.— Wing, 257-273 (266.2); tail, 99-109.5 (103.8); ex- 

 posed culmen, 28-33 (31.2); tarsus, 32-36 (33.8); middle toe, 28-32 

 (30.3).« 



Adult female. —Wing, 247-274 (259.7); tail, 97-108 (101); exposed 

 culmen, 28.5-32 (30.1); tarsus, 33-35.5 (34); middle toe, 28.5-32 

 (30.5).'' 



Breeding in Alaska (Fort Yukon; Nulato), Yukon (upper Polly 

 River), northern Mackenzie (vicinity of Fort Anderson), and in 

 extreme northwestern corner of British Columbia (Atlin) : ^ migrating 

 southAvard over practically the whole of North America to extreme 

 southern United States and northern Mexico (La Paz, etc.. Lower 

 California; Mazatlan, Siiialoa, March, Dec; La Barca and Gua- 

 dalajara, Jalisco; Guanajuato; Gulf of Progreso, Yucatan); wintering 

 northward to South Carolina (more rarely to Long Island or even, 

 very rarely, to Maine) and southern Washington; casual or accidental 

 in Bermudas (Jan. 27 and Dec. 15, 1849, and Jan., 1876), western 

 Peru (Tambo Valley), Hawaiian Islands (Poli-hula Lake, Kauai, 

 Mar. 15, 1891), and in western Europe (England, Scotland, Cornwall, 

 Ireland, and Helgoland). 



Sterna Philadelphia Ord, in Guthrie's Geography, 2d Am. ed., ii, 1815, 319 (near 

 Philadelphia, Pennsylvania). 



Chroicocephalus Philadelphia Lawrence, in Baird, Rep. Pacific R. R. Surv., 

 ix, 1858, 852; Mem. P>ost. Soc. N. H., ii, 1874. 317 (Mazatlan, Sinaloa, Mar. 27, 

 1868).— Baird. Cat. N. Am. Birds. 1859, no. 670.— Cooper and Suckley, 

 Rep. Pacific R. R. Surv., xii, pt. ii, 1860, 276 (Puget Sound, Wasliingtou, 

 resident).— CouES, Proc. Ac. Nat. Sci. Phila., 1861, 247 (Gulf of St. Lawrence; 

 habits); 1862, 310 (monogr.); Check List, 2d ed., 1882, no. 788.— Blakiston, 

 Ibis. 1862. 10 (Hudson Bay. Aug. 12). — Dall and Bannister, Trans. Chicago 

 Ac. Sci., i, 1869, 305 (Fort Yukon, Sitka, etc., Alaska).— Newton, Proc. 

 Zool. Soc. Lond.. 1871, 57, pi. 4, fiig. 6 (egg).— Allen, Bull. Mus. Comp. 



« Nine specimens. 



^ Ten specimens. 



<= Professor Cooke (Distribution and Migration of North American Gulls and their 

 Allies, 1915, 57, 58) discredits alleged breeding records for other localities, among 

 them places in southern British Columbia, Alberta, Manitoba, southern Keewatin, 

 North Dakota, Minnesota, and Michigan. 



