CLASS SECOND-BIRDS. 



Vertehralcd animals with red and loarm blood, respiring by lungs, and the 

 young of which are produced from eggs. Body covered ivith feathers, and 

 general conformation organized for flymg. 



The arrangement of birds into orders, has for its basis the conformation 

 of the bill and feet ; which are adapted to their different modes of living 

 and food. Birds of prey are characterized by a hooked bill, and feet armed 

 Avith strong and crooked nails. Climbers are those, the structure of whose 

 feet is calculated for motion on an inclined or vertical surface ; and web- 

 footed birds are evidently adapted for swimming. Others, again, have the 

 legs very long and naked, for wading ; and a large number, with the claws 

 short and feeble, live chiefly on insects. But though it be thus easy to 

 separate the more strongly marked groups into extended families, yet it 

 has been found extremely difficult to distribute them in subordinate groups, 

 .so as to facilitate the know"ledge of species in a class so widely extended. 

 In adopting the arrangement of Temminck, therefore, though his orders 

 are more numerous, than those proposed by Cuvicr and Vieillot, yet the 

 families of the latter are in much greater number ; and in an elementary 

 work, it has been judged proper to follow that system which involves the 

 least change of the established nomenclature, as likely to be most gene- 

 rally useful. 



Birds support themselves, and direct their flight in the air, nearly in the 

 same manner as fishes do in the water. But they are also calculated for 

 motion on the ground ; some families for motion on the surface of the 

 water, or even, to a certain degree, through a mass of the same element ; 

 and their structure is varied to suit these different kinds of motion. 



The part of the spine in birds which corresponds to the back, is immov- 

 able, and the only portions of the vertebral column capable of motion, are 

 the vertebraj of the neck, and those of the tail. Their pectoral members, 

 or arms, are elongated to wings, proper only for flight. These members, or 

 wings, composed of one long finger and the vestiges of two others, are 

 furnished with long, stiff, but elastic feathers, disposed like a fan, which 

 follow the movement of the bone, and, when extended, occupy a large 

 surface. The wings are attached by a double clavicle, and are supported 

 by a broad sternum, carinated in front like the keel of a ship. This sternum 

 is formed of five pieces firmly joined together ; and the greater or less 

 ossification of these pieces, is always relative to the powers of the bird for 



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