382 NATATORES. 



much the lightest and most handsomely made bird of the 

 genus. Its length, including the tail, is about the same as 

 that of the last species, that is, twenty-one inches; but twelve 

 inches of that are occupied by the tail, which reduces the 

 head and body to nine inches, while those of the other species 

 measure twelve. The cube of three to the cube of four, or 

 twenty-seven to sixty-four, is, therefore, the proportion in 

 weight of the two birds : and as the Arctic species is more 

 slender in proportion to its length than the others, it does 

 not weigh above a third as much. This circumstance alone 

 might have prevented the one bird from being mistaken for 

 the other, even though, in other respects, they were not so 

 different as they are. 



The Arctic skua has the cap of the head dark blackish 

 brown, but not reaching below the eyes; the general colour 

 of the upper part is clear brownish grey, the quills and tail 

 feathers being darker. All the under part is pure white, 

 except towards the vent and under tail-coverts, where it 

 passes into greyish ash. The sides of the neck are of a 

 delicate straw yellow. The plumage of the mature males 

 and females is nearly the same ; but that of the young birds 

 is brown and mottled. 



One of the most remarkable external characters of these 

 birds, is the length and pointedness of the middle feathers of 

 the tail and the quills of the wings. It has been already 

 mentioned that the tail is a foot long, or three inches longer 

 than the body and head; and the middle feathers, which 

 taper to a point at the extremity, are six inches and three 

 quarters longer than the others. This remarkable elongation 

 and pointedness in the flying apparatus of these birds, gives 

 them something of a tern-like appearance : and they can turn 

 on the points of their wings something after the manner of 

 swallows, though, like the rest of the genus, they live rather 

 by robbing other birds than by fishing for themselves. It 



