HORNBILLS. 



173 



fluid than those of any other birds ; for Professor 

 Owen found that air passed into the extreme 

 bones of the wing, and into the joints of the toes. 

 The eyelids are fringed with stout and stiff lashes, 

 the object of which may be to protect the eyes 





from particles of dust and rotten wood falling on 

 them, when engaged in excavating decayed trees 

 for the purpose of incubation. The Crotophaga, 

 whose beak presents an analogy to that of the 

 Hornbills, has the eyes similarly protected : this 

 bird, however, does not excavate trees. 



