BIRDS OF NORTH AND MIDDLE AMERICA. 6538 
b. Head with at least forehead and chin white; wing with a conspicuous white 
bar (across tip of secondaries). 
ce. Under parts, rump, and upper tail-coverts white. (Coast of Chile and Peru.) 
Blasipus belcheri (extralimital).¢ 
ce, Under parts, rump, and upper tail-coverts gray. 
d. Whole head, together with upper hindneck, white; tail black (except 
extreme base), tipped with white; upper tail-coverts conspicuously 
paler gray than back; bill heavier, reddish with extreme tip black or 
dusky. (Pacific coast, from Vancouver Island to Guatemala.) 
Blasipus heermanni (p. 654). 
dd. Head gray passing into white on forehead and throat; tail gray with a sub- 
terminal band of black; upper tail-coverts not conspicuously paler gray 
than back; bill smaller, wholly blackish. (Coast of Chile and Peru.) 
Blasipus (?) modestus (extralimital).} 
bb. Head dark sooty gray or dusky; wing without a conspicuous white bar; tail 
uniformly gray (in subadults with or more less admixture of black subter- 
minally). (Galapagos Archipelago.) ........-. Blasipus fuliginosus (p. 656). 
aa. Upper and under parts buffy brown, olive-brown, or fuscous, in younger birds 
with more or less distinct buffy margins to feathers of back and breast; tail 
slaty blackish or dusky brown, except at extreme base; head without white. 
(Young.) 
b. Bill heavier and lighter in color, only the tip or a subterminal band blackish. 
c. Under parts paler, always with much admixture of white on abdomen; upper 
tail-coverts mostly white (wholly so in younger birds); head dark brown, 
older birds with a pale nuchal collar strongly contrasted with color of back; 
bill much stouter.....-......-..--- Blasipus belcheri, young (extralimital). 
ec. Under parts darker, with little if any admixture of white on abdomen; upper 
tail-coverts with only slight edgings of white (uniform gray in older birds); 
head little if any darker than general color, and nape without distinct (if any) 
pale collar; bill weaker.........-..-- Blasipus heermanni, young (p. 654). 
bb. Bill weaker and uniform in color (brown or dusky) throughout. 
c Bill heavier, the exposed culmen 40; subadults with head dark mouse gray, this 
color extending down hindneck to back. ..Blasius fuliginosus, young (p. 657). 
cc. Bill weaker, the exposed culmen less than 40; subadults with head drab, some- 
times with a darker collar round upper neck. 
Blasipus (?) modestus, young (extralimital). 
@ Larus belchert Vigors, Zool. Journ., iv, 1829, 358 (coasts of Chili and Peru); Zool. 
Voy. ‘Blossom,’ Birds, 1839, 39; Sclater and Salvin, Proc. Zool. Soc. Lond., 1871, 
575¥(monogr.); Saunders, Cat. Birds Brit. Mus., xxv, 1896, 226.—Adelarus belchert 
Bruch, Journ. fiir Orn., 1853, 107.—[Leucophzus] belcheri Bonaparte, Compt. Rend., 
xlii, 1856, 771; Consp. Av., ii, 1857, 232—[Zarus] melanurus (not of Temminck) 
Lichtenstein, Nom. Av. Mus. Berol., 1854, 99 (Peru).—Larus fuliginosus (not of 
Gould) Cassin, Orn. U. 8S. Expl. Exped. (Wilkes), 1858, 378 (Cape Horn to Callao).— 
Larus frobeenit Philippi and Landbeck, Wiegmann’s Archiv fiir Naturg., 1861, i, 292 
(Arica, Chili); Anal. Univ. Chili, xxxi, 1868, 288. 
b Larus modestus Tschudi, Wiegmann’s Archiv fiir Naturg., 1843, pt. i, 389 (coast of 
Peru); Fauna Peruana, Aves, 1845-46, 53, 306, pl. 35; Reichenbach, Natat. Novit., 
1852, p. xii, pl. 275, fig. 2284; Sclater and Salvin, Proc. Zool. Soc. Lond., 1871, 573 
(monogr.); Saunders, Proc. Zool. Soc. Lond., 1878, 183 (monogr.); Taczanowski, Orn. 
du Pérou, iii, 1886, 449.—[Chroicocephalus] modestus Lichtenstein, Nom. Av. Mus. 
Berol., 1854, 98.—[Epitelolarus] modestus Heine and Reichenow, Nom. Mus. Hein. 
Orn., 1890, 359.—Larus bridgesi Fraser, Proc. Zool. Soc. Lond., 1845, 16 (Valparaiso, 
Chile; type now in coll. Brit. Mus.); Zool. Typ., 1849, pl. 69; Reichenbach, Natat. 
Novit., 1852, p. xviii, pl. 281, fig. 2317.—Blasipus bridgesi Brueh, Journ. fiir Orn., 
1853, 108. 
