LARID.E— THE GULLS AND TERNS. 237 



Genus XEMA Leach. 



Xema "Leach," Ross's Voy. App. 1819, p. lvii. Type, Larus sabinii Sab. 



Gen. Chab. Tail emarginate. or slightly forked; otherwise like the smaller species of 

 Larus. 



This genus contains a single species, the Fork-tailed or Sa- 

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

 (Creagrw fureatus) , 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 GULL. 



Popular synomym. Pork-tailed Gull. 



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



Xema sabini Edw. & Beverl. App. Ross's Voy. Baff. Bay, 4to ed. 1819, lvii. 



Xema sabinii Lawb. in Baird's B. N. Am. 1858. 807.— Baird. Cat. N. Am. B. 1859, No. (etO.- 



Saunders, P. Z. S. 1878, 209— Coues. 2d Cheek List, 1882, No. 790 — R. B. & R. Water 



B. N. Am. ii, 1884, 2o9— A. O. U. Cheek List, 1886, No. 62.-Ridgw. Man. N. Am. B 



1887, 38. 

 Xema sabinei Coues, Proc. Acad. Nat. Sci.Phila. 1802, 311; Key, 1872, 317; Check List, 1873. 



No. 558; B. N. W. 1874, 6G0— Ridgw. Nona. N. Am. B. 1881. No. 677. 

 Xema coHaris "Schreibers." Ross, in App. Ross's Voy. Baff. Bay, ii, 8vo. ed. 1819, 164 



(nee Schreibers, = ltht>dostethia rosea! Cf. Saunders, P. Z. S. 1878, p. 209). 



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

 New York, the Great Lakes, Kansas, and the Great Salt Lake, Utah. Very abun ant in 

 Alaska. Bermudas, one instance (Saunders). Macabi Island, coa~t of Peru, lat. 8° S. (one 

 specimen, fide Saunders, P. Z. S. 1878, p. 210). * 



Sp. Chab. 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 n>'ek. entire lower 

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

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

 (nearly the same shade as in Larus franklinii) the secondaries pure \hite, becoming grad- 

 ually pale grayish blue toward"base«; most of tho exposed portion of the greater coverts 

 also white, forming, together with the secondaries, a conspicuous longitudinal whie stripe 

 on the closed wing. Four ou'er prima 1 les black, broadly tipped with white, the inner weba 

 broadly margined with tho same; fifth quill with tho greater part of tho inner web. and 

 about 1.75 inches o r tho terminal portion of the outer, white, ihe remainder black; remain- 

 ing quills white; outer border of the wing, from the carpal joint back to the primary 

 coverts, including the latter and the alulffl, uniform black. BUI black, tipped with yellow; 

 eyelids re i ; iris brown; feet dull lead-color, claws blaok" (L. H. Turner, M.S.). Adult, in 

 winter: Similar to tho summer plumage, but head and n ck white, except occiput, nape, 

 and auricular region, whioh are dull dusky pmubeous. Young, first plumage: Crown, 

 nape, baok, scapulars, wing-coverts, and rump brownish gray, each feather bordered ter- 

 minally with light fulvous or pale grayish bull, this fulvous border preceded on the tertials. 



