LAHIDiE— THE OULL8 AND TERNS. 23t 



Genus XEMA Leach. 



Xema "Leach," Ross's Voy. App, 1819, p. Ivii. Type, Lams sabinii Sab. 



Oek. Chab. Tailemarginate, or slightly forked: otherwise lilce the smaller species of 

 Larus. 



This ojeiius contains a single species, tlie Foriv-tailed or Sa- 

 bine's Gull (X sabinii). Another species, the Swallow-tailed Gull 

 {Creagncs furcatus), of the Galapagos Archipelago has often been 

 referred to the genus, but the differences of structure between 

 the two are so marked as to require its reference to a different 

 genus. (See Proc. U. S. Nat. Mus., Vol. XII., 1889, p. 117.) 



Xema sabinii (Sabine). 



SABINE'S GITLL. 



Fopnlar synomjon. Fork-tailed Gull. 



Larus sabinii J. Sab. Trans. Linn. Poc. xii, 1818. 520. pi. 29. 



Xema sahini Edw. & Beterl. App. Ross's Voy. Bail. Bay, 4to ed. 1819. Ivii. 

 Xema sabinii Lawb. in Baird's B. N. Am. 1S58. 8J7.— Baibd. Cat. N. Am. B. 18.".9, No. cm.— 

 Saunders. P. Z. S. 1878. 209.— Coues. 2d Chock Li«l, 1882, No. TiiO.— B. B. & R. Water 

 B. N. Am. ii, 1884. 209.— A. O. U. Check List, 1886, No. C2.-RlDOW. Man. N. Am. B, 

 1887, S8. 

 JTema safcinei CoOES, Proc. Acad. Nat. Sci.Phila. 1862, 311; Key, 1872. .317; Check List, 1873, 

 No. .'■58: B. N. W. 1874, 6G0.-RiDO\v. Nom. N. Am. B. 1831. No. 677. 

 Xema co'laris "Schkeibers." Ross, in App. Ross's Voy. Baff. Bay. il. 8vo. ed. 1819,164 

 (nee ScHREiBEn8. = /irA')do.s(e/7ua rosea! Cf. Saunders. P. Z. 8. 1878, p. 209). 

 Hab. Circumpolar Recions; in winter migrating south, in America, to Massachusetts, 

 New York, th" Groat Lakes, Kansas, and the Great Salt Lake, Utah. Very aliun^'ant in 

 Alaska. Bermudas, one instance (Saunders). Macati Island, coast of Peru, lat. 8° S. (one 

 specimen, ./ide Saunders. P. Z. 8. 1878, p. 210). 



8p. Chae. Adult, in summer: Head and upper part of neck plumbeous, bounded 

 below by a well-defined collar of black, widest behind; lower part of the neck, entire lower 

 parts, tail, upper tail-coverts, and lower part of rump snow-white, the lower part faintly 

 tlnced with delicate rose pink in some freshly killed specimens. Mantle deep bluish gray 

 (nearly the same shade as in Larus yrunfriinii) the secondaries pure Ahite, befomingmad- 

 ually pale grayish blue toward base-'; most of the e.xposed portion of the greater coverts 

 aUo white, forming, together with the secondaries, a conspicuous longitudinal whio stripe 

 on the closed wing. Four ouer iirima irs black, broailly tipp' d ivith white, the inner webs 

 broadly margined with the same: fifth quill with the greater part of the inner web. and 

 about 1.75 inolios o' the terminal portion of the outer, white, the remainder black; remain- 

 ing audls white; outer border of the wing, from the carpal joint back to the prlin.iry 

 coverts, including the lait'T and the alulre. uniform black. Bill black, tipped with yellow; 

 eyelids re I; Iris brown; feet dull lead-color, claws black" (L. M. Turner, M.S.). Adult, in 

 winter: Similar to the summer plumiiee, but head and n ck white, except occiput, nape, 

 and auricular region, which are dull dusky p.umheous. Young, first jilumage: Crown, 

 nape, Ijack, scapulars, wing-coverts, and rump brownish gray, each feather bonlered ter- 

 minally with light fulvous or pale grayish buS,this fulvous border preceded on the tertisls. 



