384 STERNUM OF THE AGAMI. 



but they all agree in being, to a very considerable 

 extent, air-birds ; though none of them, the genus 

 lestris excepted, find their food in the air on the wing; 

 and these do not find their own prey in that element, 

 but live upon the food of other birds, which they make 

 these disgorge from their stomachs, and catch it ere it 

 falls. Gulls and terns are the races which are chiefly 

 robbed in this manner, and so prone are they to offer this 

 sort of boon or bribe to real or supposed enemies, that, 

 even in a state of confinement, they will disgorge the 

 contents of their stomachs at the sight of an eagle, or 

 any other formidable rapacious bird. Even the petrels, 

 whose habits are too much seaward for encountering 

 predatory or even plundering birds, have this dispo- 

 sition ; for when they are compelled, as they often are 

 during severe weather, to alight on the decks or 

 rigging of ships, they instantly make a votive offering 

 of the quantity of oil with which their stomachs are 

 loaded. 



The habits of long-legged birds are so diversified 

 they are so much on the land in certain cases, and on 

 the waters or by the sides of them in others that it is 

 not easy to select any species as a fair average of the 

 whole ; but they follow the general law in having the 

 sternum short in proportion as they are more on the 

 wing, having that bone more elongated, and narrower 

 in proportion, as they are more of walking birds in open 

 places which have not water, and in having the 

 posterior part more divided by notches, in proportion 

 as they are more aquatic. 



STERNUM OF THE AGAMI. 



These birds are certainly not a little anomalous ; 

 and though they are usually classed with the cranes, 

 to which they have scarcely any other point of resem- 



