GREAT SKUA. 89 



The series in the. British Museum varies from the typical 

 Gull's egg of clay-brown with distinct overlying spots of dark 

 brown and underlying spots of grey, to bluish-grey or creamy- 

 buff, with the markings faint or very much emphasized. In 

 the faintly-spotted eggs, the grey underlying spots are the most 

 prominent, and in some instances the larger end of the egg is 

 blotched with black. Axis, 2-2-2-35 inches; diam., 1-5-1 7. 



THE SKUAS. FAMILY STERCORARIID^E. 



In structure the Skuas differ markedly from the Larida, 

 and their habits more resemble those of Frigate-Birds than 

 Gulls, though some of the larger species of the last-named 

 family are robbers by nature. These redeem their character, 

 however, by other milder traits, whereas the Skuas are among 

 the most predatory of sea- fowl. They differ from the Gulls 

 and Terns in osteological characters, having only one notch 

 in the posterior margin of the sternum, and the bill is 

 furnished with a very elongated "cere," and is formidably 

 hooked, while the claws are more like those of a bird of prey 

 than those of a sea-bird, being strongly curved and very sharp. 

 Two genera are contained within this Family, both of which 

 are represented in the British Avi-fauna, and are described 

 below. 



THE GREAT SKUAS. GENUS MEGALESTRIS. 



Megafestris, Bp. Cat. Parzud. p. n (1856). 

 Types, M. catarrhactes (Linn.). 



The members of the genus Mega/esfris are four in number, 

 one of them, M. catarrhactes, inhabiting the northern ocean, 

 while another, M. macconnickii, is only known from Victoria 

 Land in the Antarctic Ocean. M. chilensis inhabits the 

 southern coasts of South America, and M. antarctica is found 

 in the southern ocean from the Falkland Islands eastwards to 

 New Zealand. The principal points of difference between the 

 species of Megalestris and Stercorarius consist in the larger 

 bulk of the former and the shorter tail, the central feathers of 

 which do not project more than half an inch beyond the rest, 

 whereas in Stercorarius this prolongation of the middle tail- 



