WINGS AND THEIR APPENDAGES. 21 



short, rounded, concave wing, is mostly peculiar to 

 birds of terrestrial habits, as it will at once be seen 

 that this form is least adapted to extensive progress 

 through the air. The wings of the Partridge and 

 Pheasant are of this shape. 



Appendages of various kinds arc occasionally at- 

 tached to the wings of birds: the direct uses of 

 these cannot readily be ascertained. We must there- 

 fore conclude that they were designed rather as or- 

 naments than to minister to the comfort or conveni- 

 ence of the bird. In the Leona Night Jar, a bird 

 allied to the Night Hawk, and a native of Africa, 

 from the centre of the upper wing coverts issues a 

 slender flowing shaft about twenty inches in length, 

 and tipped for about five inches with a broad web. 

 In some the scapularies are elongated into delicate 

 and graceful plumes, as in the Heron and Crane. 



While, as has been shown, most birds possess the 

 power of flight in a greater or less degree, yet there 

 are a few species to which it has been wholly denied. 

 This is in consequence of two separate peculiarities 

 in the development of those organs which are so 

 nicely adapted to their aerial habits. In the Ostrich 

 and Emu we see merely the rudiment of a wing, des- 

 titute of the ordinary bony and muscular structure; 

 and in the Penguin and Auk, the wing, although 

 possessed of considerable muscular power, is con- 

 verted into an organ of aquatic progression, and is 

 covered with close, stiff, and scale-like feathers. 



The tail also exerts considerable influence in guiding 

 the motions of the bird through the air, acting as a 



LIO 



