CLASS AVES: OEDEE LOKGIPENKES. 



157 



Laridse. The Gulls 

 are cosmopolitan and the 

 true scavengers of the 

 ocean. The Great Black- 

 lack is typical of those 

 which visit the Atlantic 

 coast. It feeds upon fish, 

 and sometimes upon small 

 birds or quadrupeds. The 

 Skua is remarkable for its 



. T V 1 1 1 1 J 



stout, cered bill, hooked 



upper mandible, and pirat- 



ical habits. Like the White-headed Eagle among the Fish- 



hawks, it pursues birds of its own family, and forces them 



Fig. 



Stercoranus parasi.twis, Arctic Skua. 



Sterna wilsoni, Wilson's Tern. j. 



to give up their booty ; 

 and sweeping down with 

 the velocity of an ayrow, 

 catches it before reaching 

 the water. The Tern has 

 long, pointed wings, a 

 forked tail, and slender, 

 straight bill. The grace- 

 ful evolutions of this 

 " Swallow of the Sea," as 

 it skims along the sur- 

 face, are a perpetual de- 

 light to the observer. 

 The Scissors-Mi has its 

 long, lower mandible com- 

 pressed laterally to the 

 shape and sharpness of a 

 knife-blade,* while it shuts 

 into the grooved edge of 



more. Nine-tenths of adult speci- 

 mens are thus infested, and yet are 

 in apparently good health. 



* This cultrate edge is specially 

 useful in cutting off the contractor 



