AVES. 117 



Division of the Class of Birds into Orders. 



Their distribution is founded, like that of the Mammalia, on the 

 organs of manducation or the beak, and on those of prehension, that is 

 on the beak, and particularly on the feet. 



The first that arrest our attention are the palmated feet, or those in 

 which the toes are connected by membranes, which, distinguish all 

 swimming birds. The position of these feet behind ; the length of the 

 sternum ; the neck, often longer than the legs to enable it to reach the 

 ground ; the dense, polished plumage, impermeable to water, all concur 

 with the feet in making good navigators of the Palmipedes. 



In other birds, which most commonly are partially web-footed, at 

 least between the external toes, we observe elevated tarsi ; legs divested 

 of feathers at their lower extremities ; a long thin shape j and, in fine 

 all the requisites for wading along the shores of rivers to seek their 

 food. Such, in fact, is the regimen of the great number ; and although 

 some of them inhabit dry grounds, they are called shore birds, or waders. 



Among the true land birds, the gallinacece, like our domestic cock, 

 have a heavy carriage, a moderate beak, the upper mandible of which 

 is arched ; the nostrils partly covered by a soft and inflated scale ; the 

 toes almost always indented on the edges, and short membranes between 

 the bases of the anterior ones. They fly heavily, and but a short dis- 

 tance at a time. Their chief food is grain. 



Birds of prey have a hooked beak, the point of which is sharp, and 

 curved downwards ; the nostrils pierced in a membrane which invests 

 the whole base of that beak, and feet armed with vigorous talons. They 

 live on flesh, pursue other birds, and are consequently, for the most 

 part, vigorous in flight. The great number have still a slight web 

 between the external toes. 



The Passerines comprises many more species than all the other fami- 

 lies ; but their organisation presents so many analogies that they cannot 

 be separated, although varying greatly in size and strength. Their two 

 external toes are united at the base, and sometimes for a part of their 

 length. 



Finally, the name of Scansorice, or climbing birds, has been given to 

 those whose external toe, like the thumb, is directed backwards, because 

 the greater number profit by a conformation, so favourable to a vertical 

 position, to climb trees. 



Each of these orders is subdivided into families and genera, and 

 principally from the conformation of the beak. 



