8 PIGEONS. 



breast-bone to the humerus, and, when they contract, pull down the wing with 

 extraordinary force. The muscles that raise the wing are not shown in this figure : 

 they are much slighter, and, consequently, act with much less force. 



The annual change of the flight- feathers takes place in the autumn. The mode 

 in which this is arranged, so as not to interfere with the efficiency of the wing as 

 an organ of flight, is most admirable. The moulting of the wing commences with 

 the tenth or last flight-feather, or primary, and a new feather is produced so as to 

 supply its place. A few days before this attains its full length, the ninth primary 

 is shed, and subsequently the eighth, and so on to the first. The secondaries 

 are replaced in a similar manner, only that the process commences with the first 

 secondary and proceeds gradually to the twelfth. The effect of this arrangement 

 is, that the efficiency of the wing as a means of flight is never seriously interfered 

 with, as the loss of one feather at a time has no great effect in impairing the 

 action of the limb. 



The feathers of the tail are usually twelve ; but in some of the domestic 

 varieties the number is very greatly increased, occasionally to even three times 

 that amount. The use of the tail is to support the hinder part of the body during 

 flight. The tail, being held inclined obliquely downwards, presses, during the 

 forward flight, against an inclined plane of air, and thus tends to raise the hinder 

 part of the body — a support which is required, inasmuch as the wings are placed 

 at the fore part of the trunk, far in advance of the centre of gravity of the whole 

 body. The utility of the tail during flight is strikingly shown in the difference 

 with which a pigeon flies after it has lost its tail-feathers : the action of the wings is 

 much more rapid, the flight laboured in the extreme, and the bird so mutilated is 

 left behind by the other birds of the flock in their rapid flight. The statement 

 that the tail can be made to act like a rudder, in directing the course of flight, 

 is often made by compilers of works on natural history, and repeated even in a 

 work of as high authority as Owen's " Anatomy of Vertebrates." It is, however, 

 entirely destitute of any foundation in fact. Birds turn, during flight, by striking 

 the air more forcibly with one wing than the other. 



The general character of the plumage of the pigeons differs greatly from that of 

 the true poultry. The tube or quill of the body-feathers is generally short, and 

 the shaft increases considerably in size towards the middle of its length, and then 

 diminishes very rapidly towards the end. The whole of the feathers of the pigeon 

 are destitute of the small second feather or accessory plumule, which is found 

 growing at the top of the tube of the feathers of the true poultry birds. These 

 peculiarities of plumage are sufficiently strongly marked to render the recognition 

 of the feather of a pigeon certain to an observant naturalist. 



The digestive organs in pigeons, Figure V., are strongly characterized by struc- 

 tural peculiarities distinct from those of other birds. The bill is small, slightly 

 curved, and covered at its base by the membrane of the nostrils, which is scurfy 

 and bare of feathers, the nostrils themselves being long and narrow. Contrary to 

 the arrangement that is found in most birds, the bony frame-work of the upper 



