BIRDS OF NORTH AND MIDDLE AMERICA. 653 



b. Head with at least forehead and chin wliite; wing with a conspicuous white 

 bar (across tip of secondaries). 

 c. Under parts, rump, and upper tail-coverts white. (Coast of Chile and Peru.) 



Blasipus belcheri (extralimital).a 



cc. lender parts, rump, and upper tail-coverts gray. 



d. Wiiole 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). 

 (Id. 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 fullginosu-s (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 mthout white. 



(Young.) 



b. Bill heavier and lighter in color, only the tip or a subterminal band blackish. 



c. Under parts paler, always witli 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) . 



cc. 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. . .Blasiusfuliginosus, young (p. 657). 

 cc. Bill weaker, the exposed culmen less than 40; su1)adults with head drab, some- 

 times with a darker collar round upper neck. 



Blasipus (?) modestus, young (extralimital). 



o Larus belcheri Vigors, Zool. Journ., iv, 1829, 358 (coasts of Chili and Peru); Zool. 

 Voy. 'Blossom,' Birds, 1839, 39; Sclater and Sahan, Proc. Zool. Soc. Lond., 1871, 

 575T(monogr.); Saunders, Cat. Bii-ds Brit. Mus., xxv, 1896, 226. — Adclarus belcheri 

 Bruch, Journ. fiir Orn., 1853, 107. — [Leucophaeus] belcheri Bonaparte, Compt. Rend., 

 xlii, 1856, 771; Consp. Av., ii, 1857, 232. — [Larus] melanurus (not of Temminck) 

 Lichtenstein, Nom. Av. Mus. Berol., 1854, 99 (Peru). — Larus fuliginosus (not of 

 Gould) Cassin, Orn. U. S. Expl. Exped. (Wilkes), 1858, 378 (Cape Horn to Callao).— 

 Larus frobeenii Philippi and Landbeck, Wiegmann's Archiv fiir Naturg., 1861, i, 292 

 (Arica, Chili); Anal. Univ. Chili, xxxi, 1868, 288. 



^ Larus modestus Tschudi, Wiegmann's Archiv fiir Naturg., 1843, pt. i, 389 (coast of 

 Peru); Fauna Peruana, Aves, 1845-46, 53, 306, pi. 35; Reichenbach, Natat. Novit., 



1852, p. xii, pi. 275, fig. 2284; Sclater and Salvin, Proc. Zool. Soc. Lond., 1871, 573 

 (monogr.); Saunders, Proc. Zool. Soc. Lond., 1878, 183 (monogr.); Taczanowski, Orn. 

 du P^rou, 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, pi. 69; Reichenbach, Natat. 

 Novit., 1852, p. xviii, pi. 281, fig. 2^17 .—Blasipus bridgesi Bruch, Journ. fiir Orn., 



1853, 108. 



