IVORY GULL. 
8l 
habits of the Greater Black-backed Gull, and moves with more 
energy. The nature of the Iceland Gull resembles more that 
of the Herring-Gull ; its deiiortment and flight are more grace- 
ful ; it hovers over its prey, is somewhat greedy, always active, 
and is not afraid to fight with equal, or superior, antagonists 
for its food.” 
Nest. — Has apparently not been described beyond the fact 
that it is a depression in the bare ground or on the ledges of 
precipices (Cf. Saunders, l.c.). 
Egg'S. — Two or three in number, laid early in June. The 
British Museum contains several specimens from the Seebohm 
and Gould collections. They are very similar to the eggs of 
Z. hypefboreus, but are rather smaller, and have the ground- 
colour dark clay-brown, spotted all over with chocolate-brown, 
and with very evident underlying spots of purplish-grey. Some 
have the ground-colour greyish-olive, and on this type of egg 
the spots and blotches are very distinct and plentifully dis- 
tributed over the surface of the egg. A.\i.s, 2 7-2 '9 inches ; 
diam., '85-1 -2. 
THE IVORY GULLS. GENUS PACOITIILA. 
Fagflpliila, Kaup, Natiirl. Syst. pp. 69, r96 (1829). 
Type P. eburnea (Phipps). 
The beautiful Ivory Gull is the sole representative of the 
genus Pagophila, which is thoroughly Arctic in its habitat. Its 
uniform snowy plumage finds a curious parallel in the Antarctic 
Snowy Petrel (Pagodroma niveci) of the Southern Ocean. The 
genus Pagophila is characterised by the square tail, the hind- 
toe joined to the inner one by a strong, serrated membrane, 
all the nails being large and curved, the" webs and toes being 
rugose, while the tibia is feathered nearly to the tibio-tarsal 
joint. (Saunders, Cat. B. Brit. Mus. xxvc p. 161.) 
The genus is represented by a single species, Pagophila 
eburnea, which is circumpolar in its distribution. 
I. THE IVORY GULL. P.\G0PH1L.\ EiJURNE.\. 
Larus eburneus, Phipps, Voy. N. Pole, App. p. 187 (1774); 
Seebohm, Hist. Brit. B. iii. p. 337 (1885). 
Celosparactes eburneus, Macgill. Llrit. 13 . v. p. 508 (1852). 
15 G 
