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 are 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 
