412 C. J. Siiudevall cm the Wings of Birds. 



feathersj 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 he the least important part of the organ of flight, 

 but tliey 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. Vultm^, Aquila, Milvus, 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, 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, ^wc5f, 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, ^) 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 arc still 



