BIRDS. 
305 
bird is a quadruped. Look at a plucked pigeon, and see 
how it differs iu 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 of the 
chicken,” was not so far wrong. The bird is, in fact, a 
quadruped adapted for flight. To this end the foi - o 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 
Lreast-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 widtli 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 arc attached. 
But the stroke made by such a limb, however muscular, 
u 
