412 C. J. Sundevall on the Wings of Birds, 
feathers, and consequently broad wings (e. g. Parus, Sylvia , 
&c.), that others have them short, and that the same dif¬ 
ference occurs in the strong fliers. Thus they show them¬ 
selves to be the least important part of the organ of flight, 
but they certainly serve more than the primores to modify 
the flight. It seems clear, for example, that the birds that 
fly best, sweeping along with motionless wings, or, as it 
were, sailing forward through the air, usually in large circles 
and at an immense height, only possess this power through 
the great surface which is formed by long and numerous arm- 
feathers, e. g. Vultur , Aquila , MilvuSj Ciconia , Grus. This 
kind of flight is the most beautiful of all, and ought to be 
regarded as the most highly developed ; for, in the first place, 
these birds can continue longest in flight, and, in the second, 
they can always, when necessary, fly just as quickly as the best 
of other birds, plunge down with the rapidity of an arrow 
from the most considerable heights, &c. Shorter feathers, 
and consequently somewhat narrower wings, appear, on the 
other hand, generally to belong to birds which fly rapidly 
straight forwards. If these wings are in addition strongly 
constructed, and long in consequence of the length of the 
hand-feathers, they give the bird the power of flying strongly, 
with the faculty of flinging itself about, and turning rapidly 
within a small space, e. g. Falco, Hirundo, Cypselus y Columba , 
Cuculus. This mode of flight is equally of advantage to the 
Birds of Prey, and to those which have to evade their enemies. 
The birds which possess short wings always fly with rapid 
movements of the wings, uninterruptedly when the wing is 
narrow ( e . g. Pygopodes, Anas , Gallinse), and jerkingly when 
it is broad (e. g. a great part of the Oscines, Picus } &c.). 
We have still a few words to say upon the attachment of 
the arm-feathers. In all Song-birds they rest with the quill 
upon the whole breadth of the ulna (see fig. 1 , g) to which 
they are firmly and closely attached. In the somewhat more 
strongly constructed forms the quills are in addition so 
thick that they leave but little space between them, and pass 
with their basal ends beyond the ulna a little forward towards 
the radius; but in all (e.g. even in Parus) they are still 
