SWIMMING BIRDS. 



407 



The Gannets (Sula, and the Tropic Birds (Phaetonj are of similar 

 structure and habits, but of smaller dimensions. 



FlG. 395. THE G ANNEX. 



In the family of Lamellirostres* the beak is thick 

 and covered with a soft skin instead of true horn ; 

 its edges are furnished with ridges resembling little 



FlG. 396. BEAK OF DUCK. 



* lamella, a flat plate ; rostrum, a leak. 



