BIRDS OP NORTH AND MIDDLE AMERICA. 575 



Alaska, 1886, 124 (Aleutians and Pribilof Islands; St. Michaels, 1 spec, Sept. 



18, 1876). — American Ornithologists' UniOxV, Check List, 1886, and 2d ed., 



1895, no. 41 ; 3rd ed., 1910, p. 36.— Townsend, Cruise 'Corwin' in 1885 (1887;, 



98 (Pribilof Islands; Otter Island). — Taczanowski, M6m. Ac. 'St. Petersb. 



xxxix, 1893, 1053 (e. Siberia).— Clark (A. H.), Proc. U. S. Nat. Mus., xxxviii,' 



1910, 35 (near Unalaska Island; western Aleutians; Commander Islandc). — 



Cooke, Bull. 292, U. S. Dept. Agric, (Biol. Surv.), 1915, 21, fig. 7 (range and 



migrations) . 

 i?[isso] brevirostris Dall, Proc. Calif. Acad. Sci., v, 1873, 32 (Pribilof Islands).— 



CouES, Key N. Am. Birds, 2d ed., 1884, 748.— Ridgway, Man. N. Am. Bird.s, 



1887, 25. 

 {Larus (Laroides)] citrirostris "Scliimper" Bruch, Journ. liir Oru., 1855, 284 



(Kamchatka). 

 [/?issa] kotzehuii Bonaparte, Naumannia, 1854, 212 (western North America- 



California). 

 Larus warnecki Coinde, Rev. et Mag. de Zool., 18G0, 401 (St. Paul Island, Bering 



Sea). 



Genus PAGOPHILA Kaup. 



Gavia (not of J. R. Forster, 1788) Boie, Isis, 1822, 563. (Type, Larus eburneus 



Phipps=L. albus Gunnerus.) 

 Fagophila Kaup, Skizz. Entw.-Gesch. Eur. Thierw., 1829, 69. (Typo, by mouo- 



typy, Larus eburneus Phipps=L. albus Gunnerus.) 

 Cetosparactes Macgillivray, Man. Brit. Orn., ii, 1842, 251 . (Type, Larus eburneus 



Phipps=L. albus Gunnerus.) 



Medium-sized Larid?e (wiiig 300-362 mm.) with tarsus larger tlian 

 middle toe without claw, roughly granulated or almost serrate behind, 

 the scutella on front (as well as those of toes) large and prominent; 

 webs of feet deeply incised; longer primaries attenuated and sub- 

 falcate terminally, and color wholly pure white in adults, sparsely 

 spotted with blackish in young. 



BiU much shorter than head (the exposed culmen usually a little 

 shorter, rarely slightly longer, than tarsus), relatively stout, very 

 slightly compressed; culmen nearly straight or even faintly concave 

 basally, gradually decurved from above middle of nostril; gonys 

 haK as long as mandibular rami or slightly more, straight, ascending 

 termuially, its basal angle prominent; nostril relatively large, its 

 broader anterior end sHghtly posterior to gonydeal angle. Wing long 

 and pointed, the longest primary (outermost) exceeding tertials by 

 considerably more than half length of wing, the longer primaries 

 attenuated and subfalcate termuially. Tail more than two-fifths as 

 long as wmg, truncate. Tarsus longer than middle toe without claw, 

 about as long as exposed culmen (usually a little longer, rarely slightly 

 shorter), stout, the transverse scuteUa of acrotarsium large and prom- 

 inent, the plaiita tarsi roughly granulated or almost serrate; anterior 

 toes with thick and promuient transverse scutella, the lateral ones with 

 roughly granulated outer edges, the connecting webs of anterior toes 

 rather deeply incised; hallux well-developed (rather large for the 



