572 IVORY GULL. 



vated, the fore toes of moderate length, the fourth much longer than the 

 second, the third longest, the hind one with a single scutellum and three 

 transverse series of scales, the rest scutellate above and connected by re- 

 ticulate membranes having a concave margin, the lateral toes margined 

 externally with a narrow membrane. Claws stout, rather large, arched, 

 compressed, rather obtuse, that of middle toe with an enlarged inner edge. 



The plumage in general is close, full, elastic, soft and blended, on the 

 back rather compact. Wings very long, rather broad, acute, the first 

 quill longest, the other primaries rapidly graduated ; secondaries broad 

 and rounded, the inner tapering but rounded. Tail of moderate length, 

 even, of twelve rather broad rounded feathers. 



Bill bright yellow, greenish dusky at the base. Iris brown, edges of 

 eyelids vermihon. Feet and claws black. The whole of the plumage 

 is pure white. 



Length to end of tail 19 inches, to end of wings 20| ; extent of wings 

 41 ; wing from flexure 13^ ; tail 6j ; bill along the back l^-j, along the 

 edge of lower mandible 2; tarsus l^'^ ; middle toe 1^%, its claw ^^. 

 Weight 20 oz. 



Young of the second year, killed in September. Plate CCLXXXVII. 

 Fig. 2. 



After the second moult, the bill is pale yellow at the end, dusky at the 

 base for two-thirds of its length ; the edges of the eyelids vermilion, the 

 iris brown, the feet black. The plumage is white ; the forehead and 

 sides of the head mottled with leaden-grey ; most of the wing-coverts 

 have towards the end a spot of greyish-black, and the quills, large coverts, 

 and tail-feathers are similarly marked, the markings on the tail forming 

 a subterminal bar. 



