15. LAEUS. 25't 



30. Larus occidentalis. 



[?] Larus argeutatus, Nordm. m Annan's Ileis. um die Erde, Atlas, 



Verzeichn. Th. u. Pji. p. 18 (18;}o : California). 

 Larus occidentalis, And. Orn. Biogr. v. p. 320 (1839) ; id. Synop. 

 p. 328 (1839) ; id. B. N. A7ner. 8vo ed. vii. p. 101 (1844) ; Gray, 

 Gen. B. iii. p. 654 (1846) ; Baird, Cass., ^- Laior. B. N. Amer. 

 p. 845 (1858); Cassin, U.S. E.rpl. Evjjed. p. 247 (1858: Cali- 

 fornia); Ileinn. Pacijic R. Rep. x. pt. vi. p. 73(1859); Cooper 

 ^- SucJdci/, Nat. Hist. Wash. Terr. p. 271 (1860) ; Coues, Pr. 

 Philad. Acad. 1862, p. 296 ; id. Ibis, 1866, p. 271 (San Pedro) : 

 Schley. Mus. P.-Bas, Lari, p. 15 (1863) ; Elliot, New Sf Unjiq. 

 B. N. Amer. ii. pi. Hi. (1869); Ridyw. Bull. U.S. Nat. Mm. 

 no. 21, p. 52 (1881 ) ; Coues, -Ind ed. Check-l. N. Amer. B. p. 121 

 (1882) : Beldiny, Pr. US. Nat. Mm. v. p. 549 (18S3 : L. Cala.j ; 

 Coues, Kei/ N. Amer. B. 2nd ed. p. 744 (1884) ; Baird, Breicer, 

 ^- Ridyw! Watcr-B. N. Amer. ii. p. 230 (1884) ; Henshaw, Auk, 

 1885, p. 232 (Cala.) ; A. O. U. Check-l. N. Amer. B. p. 88 (1886) ; 

 Blake, Auk, 1887, p. .329 (Sta. Cruz I., Cala., breeds) ; Ridgw. 

 Man. N. Amer. B. p. 28 (1887) : N. S. Goss, Auk, 1888, p. 240 (San 

 Pedro Martir I., 28' N.) ; W. A. Jeffries, op. cit. 1889, p. 222 

 (Sta. Barbara, Cala.) ; R. H. Laiurence, op. cit. 1892, p. 41 

 ( Wasbinglon TeiT. ) ; Loomis, Pr. Cala. Acad. v. p. 213 (1895). 



Glaucus occidentalis, Bruch, J.f. O. 1853, p. 101. 



Laroides occidentali.'^, Bruch, J. f. O. 1855, p. 282 : Bp. C. R. xlii. 

 p. 770 (1856) ; id. Consp. Av. ii. p. 219 (1857). 



Larus arsreutatus, var. occidentalis, Coues, Key N. Arner. B. p. 312 

 (1872)'; id. Check-l. no. 547 6 (1873); id. B. N.-West, p. 633 

 (1874) ; Streets, Bull. U.S. Nat. Mus. vii. p. 25 (1877 : Lower Cala.). 



Larus fuscus ?, Saunders, P. Z. S. 1875, p. 158 (Lower California : a 

 very small femiJe). 



Adult male in hreeding-plumage. Head, neck, tail, and under 

 surface pure white ; mantle darker and of a bluer slate-colour than 

 in L. ajjinis ; secondaries similarly tipped with white ; aU the 

 primaries tipped with white, but the outer ones least; the three outer 

 ([uills chiefly black, with a white sub-apical mirror on the 1st, and 

 a white spot (or two) on the 2nd, but not a true mirror ; on the 4th 

 quill the grey "wedge" from the basal portion runs down the 

 inner web; on the 5th both webs are chiefly grey, turning whitish at 

 the apex of the wedge, followed by a black subtorminal bar ; in the 

 6th the black bar is narrower ; the upper primaries are grey with 

 white tips. Bill chrome-yellow with red angle, very stout ; eyelid 

 vermilion ; tar.si and toes yellow (in life). Total length 21-22 

 inches, culmen 2-8, wing 16"5, tail 7, tarsus 2- 7, middle toe with 

 claw 2-7. 



The female is smaller and her bill is far less robust. 



Adult in winter. Similar. Dr. Elliott Coues (' Ibis,' 18GG, p. 271) 

 says that the head of the mature bird is not streaked in this species, 

 and, so far as our material goes, he appears to be right ; but the 

 authors of the ' Wator-Birds of Xorth America ' state that in winter 

 the head is streaked. In the immature or even in the nearly adult 

 bird it is so, undoubtedly. 



Young. Upper surface dark brown, with a greyish tinge on the 



VOL. XXV. S 



