AVES. 407 



flight. The long feathers attached to what may be termed the hand, gene- 

 rally to the number of ten, are termed primaries ; the secondaries, variable 

 in number, are those attached to the fore-arm ; and the scapulars, are the 

 smaller feathers, which are attached to the humerus. In describing birds, 

 the term remiges is also used, to denote the feathers of the wings, which 

 serve as oars ; and rectrices, those of the tail, which have been considered 

 to act as a rudder. The smaller feathers, which cover the base of the wing 

 and tail, are termed tectrices. The anterior extremities, destined to support 

 them in flight, can neither be used for prehension nor support, and birds 

 thus take objects from the ground by their mouth. The neck is elongated, 

 and the body thrown forward, that the bill may easily reach the ground. 

 The pelvis is lengthened, to furnish an attachment for the muscles, which 

 support the trunk upon the thighs ; and there is an arrangement of muscles 

 going from the pelvis to the toes, in such a manner that the weight of the 

 animal bends the toes, and enables it to sleep perched upon one foot. 



The bony part of the tail is short, but it carries a row of strong feathers, 

 which, spreading, contribute to support the bird. The number of these 

 feathers is generally twelve, sometimes fourteen, and in the gallinse eigh- 

 teen. The legs have a fermur, and a tibia, and the tarsus and metatarsus 

 are represented by a single bone. The toes are attached to the tarsus, and 

 are generally three before and a kind of thumb behind ; which, however, is 

 sometimes wanting. In the swallow it is directed forwards. In the climb- 

 ers, on the contrary, the external toe and thumb are directed backwards. 

 The number of joints increases in each toe, counting from the thumb, which 

 has two, to the external toe, which has five. Birds with toes entirely free, 

 are adapted to walk or hop on a horizontal surface, such as the domestic 

 fowl. Others with two toes behind and two before, such as the parrot, 

 walk with difficulty, but climb Avith facility ; and others again, such as 

 ducks and swans, with the toes united by a membrane, are chiefly calculat- 

 ed for motion in the water. The bill in birds is covered with a corneous 

 substance, and as these animals swallow their food without mastication, 

 they are not furnished with teeth. The upper mandible is formed chiefly 

 of the intermaxillary bones, prolonged behind into two arches, of which the 

 internal is composed of the palate bones, and the external of the maxillary 

 and jugal bones; and this mandible is united to the cranium by elastic 

 laminae. The bill is constructed less for bruising the food than for seizing 

 and dividing it ; and thus from the greater solidity and length of this organ, 

 the nature of the food may be inferred. The bill, or beak, is sometimes 

 furnished at its origin, with a fleshy or membranous caruncle, which is 

 called the cere; and sometimes the beak is prolonged upon the forehead 

 into a kind of horn or helmet, as in the calao. The two mandibles move- 

 able upon one another, through the medium of an intermediate bone, placed 

 at the articulation, is a distinguishing anatomical character, in the structure 

 of the jaws of birds. The quills and feathers are composed of a bearded or 



