424 



DESCRIPTIVE CHARACTERS. 



PLUMAGE. Adult male nuptial. Head, neck, breast, ab- 

 domen, and tail, white; back and wings, dark Trench' grey 

 or lavender colour, deeper in shade than the same regions 

 of several other species of Gulls ; secondaries, broadly tipped 

 with white ; two outer pairs of primaries, chiefly dull 

 black, with grey basal portions, and with large white ' eyes ' 

 near the tips ; rest of primaries, chiefly pale grey, barred 

 below with black, and all except the first broadly tipped 

 with white. 



Adult female nuptial. Similar in plumage to the male. 



Adult winter, male and female. Differs from the nuptial 

 plumage in that the head and upper neck are streaked and 

 spotted with greyish-brown. 1 



Immature, male and female. Before August the upper 

 parts of the immature birds are dusky-brown, with dull buff 

 edges to the feathers ; throat, breast, and abdomen, impure 

 white, with brownish feathers interspersed ; tail, dull white, 

 broadly banded subterminally with brown ; upper tail-coverts, 

 white, thinly interspersed with brown; primaries, brown. 2 

 The lavender-coloured feathers of the back appear early in 

 the first autumn, but the wing-coverts retain their immature 

 brownish coloration and the tail is banded until the next 

 autumn moult. The pure white head is apparently not 

 assumed until all signs of immature plumage have dis- 

 appeared. 



BEAK. Green, tipped with yellow. 



FEET. Yellowish-green. 



IKIDES. Blackish-brown. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH 17*5 in. 



WING 14-5 



BEAK 1-85 



TARSO-METATARSUS 2 -25 



EGG 2-25 x 1-5 in. 



1 1 have seen and examined in the flesh many Common Gulls in full 

 winter- plumage as early as August 6th. 



2 Birds in this plumage are far from common along our coasts, except 

 near their breeding-colonies. 



