400 TEN YEAES IN SWEDEN. 



common skua is at once known by its size, being as long, and 

 generally thicker, than that of the lesser black-backed gull. 

 The eggs of the other three are,, however, difficult to dis- 

 tinguish. They all vary much in size, shape, and colouring; 

 but if a lot could be mixed without marking them, it would 

 be almost impossible to separate them. As far as I have 

 observed, the egg of the pomarine is usually thinner and 

 more pointed at the smaller end than the other two. But I 

 can hardly see any difference between the eggs of Richard- 

 son's and Buffon's skua, except that perhaps that of .the 

 latter is rather thicker and blunter at the large end, 

 and usually greener in colour, especially when first taken. 

 Respecting the breeding habits of the skuas in East Fin- 

 land, Sommerfeldt observes "The pomarine skua breeds 

 inland, a little way from the coast ; Richardson's skua, on 

 certain islands in the sea, and on some tolerably dry places 

 on the mainland, but does not come far into Waranger 

 Fjord. Buffon's skua breeds on the marshes near the fjord, 

 and also on the fell mosses by the side of the large Tana 

 River." 



The middle feathers of the tail elongated and pointed. 



240. L. PAEASITICA, Boie. Spetsstjertade Labben. Richard- 

 son's Skua. D. F. 



The two middle tail feathers pointed, about 3 inches 

 longer than the others ; middle toe, with claw, equal to 

 tarsus, 1 in. 6 1. ; the front edge of the nostril is much 

 nearer to the tip of the beak, than to the point of the 

 feathers on the sides of the beak. Length 1 ft. 5 in. ; 

 the side feathers of the tail 4-^. in. ; the next to them 

 5 in. ; the middle ones about 8 in. ; beak from gape 

 2 in. ; height at the root -^ in. ; breadth a little more ; 

 horn coloured, with a green tinge ; legs and feet black ; 

 iris brown ; mouth, tongue, and gape, white ; legs in the 

 young, lead coloured, toes at their bases white ; old bird, 

 mantle dark brown, becomes blue-grey with age; head and 

 neck blackish; wing feathers and tail white at the 

 roots ; temples, throat, a ring round the neck, as well 



