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 deportment 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, I.e.). 



Eggs. 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 

 L. hyperboreus, 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. Axis, 2 7-2 '9 inches; 

 diam., '85-1-2. 



THE IVORY GULLS. GENUS PAGOPIIILA. 

 Pagophila, Kaup, Natiirl. Syst. pp. 69, 196 (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 nivea) 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. xxv. p. 161.) 



The genus is represented by a single species, Pagophila 

 eburnea^ which is circumpolar in its distribution. 



I. THE IVORY GULL. PAGOPHILA EBURNEA. 



Larus eburneus, Phipps, Voy. N. Pole, App. p. 187 (1774); 



Seebohm, Hist. Brit. B. iii. p. 337 (1885). 

 Cetosparacles eburneus^ Macgill. Brit. B. v. p. 508 (1852). 



'5 o 



