SABINE'S GULL. 41 



THE FORK-TAILED GULLS. GENUS XEMA. 



Xema, Leach in J. Ross's Voy. Baffin's Bay, App. ii. p. 57 



(1819). 



Type X. sabinii (J. Sabine). 



In this genus the tail is considerably forked, and the wings 

 long, the hind-toe being free and very small. 



Only two species of Fork -tailed Gull are known, the 

 Arctic X. sabinii, and X. furcata of the Galapagos Islands, 

 which seems to wander down the Pacific coast of South 

 America, as it has been found at Paracas Bay, in Peru. 



i. SABINE'S GULL. XEMA SABINII. 



Larus sabinii, J. Sabine, Trans. Linn. Soc. xii. p. 520, pi. 29 



(1818); Seebohm, Hist. Brit. B. iii. p. 298 (1885); 



Lilford, Col. Fig. Brit. B. part xx. (1891). 

 Gavia sabinii, Macgill. Brit. B. v. p. 607 (1852.) 

 Xema sabinii, Dresser, B. Eur. viii. p. 337, pi. 593(1874); 



B. O. U. List. Brit. B. p. 193 (1883); Saunders ed. 



Yarrell's Brit. B. iii. p. 573 (1884); id. Man. Brit. B. 



p. 641 (1889) ; id. Cat. B. Mus. xxv. p. 162 (1896). 



(Plate XCVIIL} 



Adult Male in Breeding Plumage. General colour above light 

 ashy-grey, including the wing-coverts and inner secondaries, 

 the latter as well as the greater wing- coverts being tipped with 

 white, the latter very broadly, so that nearly the terminal half 

 of the external greater wing-coverts is white ; exterior lesser 

 coverts, bastard-wing, primary-coverts, and primaries black, 

 the latter tipped with white, and having the inner half of the 

 inner web longitudinally white, but this not reaching to the end 

 of the quill on the first five primaries ; the black much 

 diminished on the next two primaries, the inner primaries and 

 the secondaries being white ; the innermost secondaries light 

 ashy-grey, white at their ends ; lower rump, upper tail-coverts, 

 and tail white, the latter conspicuously forked ; head, sides of 

 face, and throat dark slaty-grey ; the hind-neck, sides of neck, 

 and under surface of body, from the lower throat downwards, 



