SILVER GULL. 107 



Larus novcehollandice gunni Mathews, Nov. Zool., Vol. XVIII., p. 212, Jan. 31st, 1912: 



Tasmania. 



Larus novcehollandice ethelce Mathews, Austral Av. Rec., Vol. I., pt. 2, p. 30, April 2nd, 1912 r 



Kangaroo Island, South Australia. 



Bruchigavia novcehollandice yorki Mathews, Birds Austr., Suppl. No. 1, Check List, p. 30, 



Feb. 16th, 1920: Torres Straits, Queensland. Nom. nov. for Gelastes gouldi Bonaparte, 1854. 



DISTRIBUTION. Australia generally and Tasmania. 



Adult male. Back and wings blue-grey ; head and neck all round and entire 

 under-surface of the body pure white including the axillaries and under tail-coverts ; 

 upper tail-coverts and tail also white as well as the small coverts round the bend of 

 the wings, both above and below ; inner under wing-coverts inclining to grey ; 

 bastard-wing and primary-coverts white ; the first primary black with a white- 

 mirror towards the end which occupies both webs, slightly fringed with black on the 

 inner one ; the second primary has a line of white near the base which occupies the 

 shaft and a small portion each side of it, a mirror near the tip similar in shape to 

 the one on the first primary but more broadly margined with black on the inner 

 web ; the third primary has a similar line of white from the base to beyond the 

 middle of the feather, and another elongated spot on the inner web which is joined 

 by the continous white shaft, also tipped with white ; the fourth quill is white on 

 the outer web for the greater part of its length, towards the end it crosses on to the 

 inner web : the basal portion of the inner web is greyish-brown near the shaft with 

 a subapical black and white tip ; the fifth primary is white on the outer web nearly 

 the whole length, dark grey and fringed with black on the inner web, with a subapical 

 black band and white tip ; the sixth quill is blue-grey fringed with black on the 

 inner web towards the end and a narrow subapical black band and white tip ; the 

 seventh primary blue-grey with a very slight fringe of black on the inner web near 

 the tip ; secondaries entirely blue-grey ; bill and feet red ; iris white, eyelid red. 

 Total length 440 mm. ; culmen 36, wing 309, tail 120, tarsus 50. 



Adult female. Similar to the adult male but smaller. 



Immature. Differs from the adult in having the tips of the feathers on the 

 nape, hind-neck, and mantle brown ; the lesser wing-coverts brown tipped with 

 white and fringed on the sides more or less with ochreous-buff, the greater coverts 

 grey with a subapical brown spot and white tip ; bastard -wing dark brown on the 

 inner web ; the secondaries grey with subapical brown marks and tipped with white ; 

 the innermost secondaries brown with grey bases irregularly marked and fringed with 

 white at the tips, also a slight mottling of buff ; some of the scapulars similarly 

 marked but paler ; the feathers of the rump grey with subapical brown spots and 

 fringed with buff at the tips ; some of the upper tail-coverts blackish at the tip ; 

 tail-feathers white with a subapical dark band mottled with buff and tipped with 

 white. As the bird advances in age the brown of the upper wing-coverts seems to 

 be the last to change. Iris light grey, eyelid orange, bill dark horn, legs and feet 

 greyish-black. 



Immature with traces of down. Channel Rock, Torres Straits, June 1st, 1881 : 

 " Iris brown, bill horn, legs and feet light brown " ; top of the head uniform light 

 brown, bases of all feathers white tipped with light brown with a penultimate bar 

 of much darker brown ; these colours increase in depth on the scapulars ; rump 

 white ; tail-feathers with white tips, penultimate brown bar and white bases ; 

 general under coloration white ; primaries black with white tips, the first two 

 primaries showing incipient mirrors (which are not present in first complete immature 

 plumage, but reappear at a later age) ; greater coverts white, the outermost with 

 irregular black markings, the next two fringed on outer web with darker brown. 

 (These are similar in immature birds, but are pure white in adult.) 



Nestling. Heavily mottled with brown on the upper-surface ; under-surface 

 white. 



Nest. Formed of a few rushes and grasses. 



