226 



Descriptive Zoology. 



who has* taken a trip by steamer has watched them and 

 wondered at their tireless flight. The gulls have hooked 

 beaks, while those of terns are pointed and nearly straight ; 

 in both the bills are often bright-colored. They feed chiefly 

 on fishes, but some are scavengers, following ships. 



The Tube-nosed Swimmers. To this order belong the 

 petrels, which resemble the gulls except in having the nos- 



FIG. 134. PETREL. 



From Eckstorm's The Bird Book. 



trils open as two parallel tubes on the top of the beak. 

 Perhaps best known, or at least most read about, are the 

 stormy petrels, or " Mother Carey's chickens." Closely 

 related also is the albatross of the southern hemisphere, 

 which has a spread of ten feet. 



