148 



ANATOMY OF VERTEBRATES. 



{Rh?/ncops) has the further peculiarity of an inequality in the length 

 of the two mandibles, the upper one being the shortest, fig. 66, so 

 that this sea-bird gets its food, which consists of floating marine 

 animals, by pushing and tilting them within the action of the 

 upi^er blade as it swims along. 



A sharp-edged beak may be as remarkable for transverse ex- 

 tension and depression, or horizontal flat- 

 tening : and such a form serves for cap- 

 turing fishes and reptiles : it is seen in 



(O the Boatbills of South America {Can- 

 croma), fig. 67, and of Nubia {Balcsni- 

 ceps). 



Of the blunt-edged bills we may first 

 notice those which are flattened hori- 

 zontally. When a bill of this description is long and strong. 



Bill of the Boatbill. 



Bill and pouch of the Pelican. 



as in the Pelican, fig. 68, it serves to seize large but feebly 

 resisting fishes. 



When it is long and weak, as in the Spoonbill, which derives 

 its name from the dilated extremity of the mandibles, it is only 



available to seize amid sand, mud, 

 or water, very small Crustaceans, 

 Mollusks, &c., fig. 69. 



The more or less flattened bills 

 of Ducks, the more conical ones 

 of Geese and Swans, and that 

 of the Flamingo, of which the extremities of the mandibles are 

 bent downwards abruptly, fig. 70, have all transverse horny 

 lamina) arranged along their edges, which when the bird has 

 seized any object in the water, serve, like the whalebone laminae 



Bill of the Sroonhill. 



