CLASS AVES: ORDEE LONGIPENNES. 



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 

 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 



Lams mannus, Great Black-backed SuU, 



Mg. 267. 



Stercorarms parasi&cus, Arctic Skna. A- 

 Mg. 26S. 



SteriM wileoni, Wilson's Tern. 



to give up their booty : 

 and sweeping down with 

 the velocity of an arrow, 

 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-bill 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 Iiealth. 



* This cultrate edge is specially 

 useful in cutting off the contractor 



