BIRDS. 



bird is a quadruped. Look at a plucked pigeon, and see 

 how it differs in the matter of limbs from a skinned rabbit, 

 except that the fore legs have no feet or toes at their tips. 

 After all, the pensioner's child, who respectfully submitted 

 that " mother didn't like always to have the hind leg oi the 

 chicken," was not so far wrong. The bird is, in fact, a 

 quadruped adapted for flight. To this end the fore limbs 

 are greatly lengthened and strengthened, as to them is 

 assigned the office of beating the air by successive strokes, 

 and thus impelling the body through that fluid, as a boat 

 is rowed by oars. Flying, like swimming, is but rowing 

 through the medium, instead of on its surface. 



In order to make these limbs effective, to render them 

 capable of long-sustained energetic action, they must be 

 moved by stout, dense, and powerful muscles. Every one 

 knows that the most fleshy part of a bird — and especially 

 of a flying bird, such as a pigeon, as distinguished from a 

 running one, such as a fowl — is the mass that lies on the 

 breast-bone. Now this mass of flesh, or rather these 

 masses, one on each side, are the great pectoral muscles, 

 one end of which is inserted on the broad surface of the 

 breast-bone, and the other end is spread along the bone of 

 the shoulder or upper-arm. For the attachment of these 

 great muscles, there must be a great breadth of surface; 

 and see how skilfully this is provided in the form of the 

 breast-bone ! It is a firm buckler of great width planted 

 across the viscera; while, as even this extent would not 

 have been sufficient, the surface is greatly increased by a 

 high keel or ridge of bone that rises from its centre, to 

 each side of which the muscles are attached. 



But the stroke made by such a limb, however muscular, 



