BLACK-HEADED GULL. 59 



V. THE BLACK-HEADED GULL. LARUS RIDIBUNDUS. 



Lams ridibuiidus^ Linn. Syst. Nat. i. p. 225 (1766); Dresser, 

 B. Eur. viii. p. 357, pis. 596 and 597, fig. i. (1878); 

 B. O. U. List Brit. B. p. 191 (1883); Saunders, ed. 

 Yarrell's Brit, B. iii. p. 594 (1884); Seebohm. Hist. Brit. 

 B. iii. p. 310 (1885); Saunders, Man. Brit. B. p. 649 

 (1889); Lilford, Col. Fig. Brit. B. part xxi. (1892); 

 Saunders, Cat. B. Brit. Mus. xxv, p. 207 (1896). 



Gavia ridibuiida^ Macgill. Brit. B. v. p. 593 (1852). 



Gavia capistrafa, Macgill. t.c. p. 605. 



{Plate XCIX.) 



Adult Male. — General colour above delicate pearly-grey, 

 including the wing-coverts ; the marginal coverts pure white, 

 as also the bastard-wing and primary-coverts, the latter slightly 

 shaded with pearly-grey on the inner feathers ; the three outer 

 primaries white, with white shafts, black tips, and black edging 

 to the inner webs ; the first primary black along the outer web, 

 the second and third also, with a narrow line externally ; 

 remainder of the primaries grey, with black tips and black 

 margins to the inner webs, the black disappearing gradually on the 

 inner primaries, which have a terminal spot of grey ; the fifth pri- 

 mary white on the outer web, the secondaries entirely grey ; lower 

 rump, upper tail-coverts, and tail white ; crown of head as far 

 as the nape, sides of the face, and throat chocolate-brown, 

 darkening towards the edges of the hood, which is very well 

 defined ; a ring of white above and behind the eye ; hind-neck 

 from the nape and sides of neck white, slightly overspreading 

 the mantle ; entire under surface of body from the lower throat 

 downward white, with a slight rosy tinge, including the 

 axillaries and marginal lower wing-coverts; the lower, median, 

 greater, and primary-coverts grey ; " bill, tarsi, and toes lake- 

 red ; iris hazel" {H. Saunders). Total length, i6"5 inches; 

 culmen, i*45j wing, 11*9; tail, 475; tarsus, 17. 



Adult Female. — Slightly smaller than the male, as a rule. Total 

 length, 14-5 inches; wing, 11 '8. 



Adult in Winter Plumage. — Differs from the summer plumage in 

 lacking the brown head, the crown being white with a Uttle 



