EXTERNAL PARTS OF BIRDS. — THE WINGS. Ill 



they are more alike and less distinctly disposed in rows or series ; so that for practical purposes 

 they pass under the general name of under wing-coverts, or lining of the wing. Since, when 

 the wing is particularly marked on the under side, it is the coverts and not the remiges that are 

 highly or variously colored, the common expression "wing helow," or " under surface of the 

 wing," refers to the coverts more particularly. We should distinguish, however, from the under 

 coverts in general, the axillmrs, or axillary feathers (Lat. oaAlla, the arm-pit). These are the 

 innermost feathers lining the wings, lying close to the body ; almost always longer, stiffer, 

 •narrower, or otherwise peculiarly modified. In ducks, for example, and many of the waders, 

 as snipe and plover, they are remarkably well developed. The color of the axUlaries is the 

 principal distinction between some species of plovers. The 



Bemiges, or Flight-Feathers (fig. 30, 6, s, and t),giv& the wing its general character, 

 mainly determining both its size and its shape ; they represent most of its surface and of its 

 inner and outer borders, and all of its posterior outline, forming a great expansion of which the 

 bony and fleshy framework is insignificant in comparison. The shape of the wing is indeed 

 primarily afleeted by the relative lengths of its bony segments, the upper arm being, in a 

 humming-bird, for example, very short in comparison with the terminal portion of the limb, 

 a,nd in an albatross again, both upper and forearm behig greatly lengthened ; still in any case 

 it is the flight-feathers that mainly determine the contour of the wing, by their absolute degree 

 of development, their lengths proportionately to one another, and their individual shapes. They 

 collectively form a thin, elastic, flattened surface for striking the air, quite firm along the front 

 border where the b(«ie and muscle lie, thence growing more mobile and resilient toward the 

 posterior border and along the outer edge. Such surface may be quite flat, as in such birds as 

 ■cut the air with long, pointed wings, like oar- blades ; but it is generally a little concave under- 

 neath and correspondingly convex above ; such arching or vaulting of the wing-surface being 

 usually associated with a short, broad, rounded wing, as in the gallinaceous tribe, and being 

 least in birds which have the thinnest and sharpest wings. Corresponding differences in the 

 mode of flight result. The short, rounded vring confers a powerful though labored flight for 

 short distances, usually accompanied by a whirring noise resulting from the rapidity of the 

 wing-beats; birds that fly thus are almost always thickset and heavy. The long, pointed 

 "wing gives a noiseless, airy, skimming flight, indefinitely prolonged, and accomplished with 

 more deliberate vring-beats ; birds of this style of wing are generally trim and elegant. These, 

 of course, are merely generaUzations of the extremes of modes of fiight, mixed and gradated 

 in every degree in actual bird-life. Thus the humming-bird, which has shaip, thin wings, 

 whirs them fastest of all birds, — so rapidly that the eye cannot follow the strokes, merely 

 perceiving a haze about the bird while the ear hears the buzzing. The combination of acute- 

 ness and concavo-oonvexity is a remarkably strong one, confeiTing a rapid, vigorous, whistling 

 flight, as that of a duck or pigeon, or the splendid hurtling of a falcon. An ample vidng, as 

 one both long and broad without being pointed is called, is well displayed by such birds as 

 herons, ibises, and cranes ; the flight may be strong and sustained, but is rather slow and 

 heavy. The longest-winged birds are found among the swimmers, pai"ticularly the pelagic 

 family of the petrels, and some of the whole- webbed order, as pelicans, particularly the frigate- 

 pelican. The last named, Taclvypetes aquilus, has perhaps the longest wings for its bulk of 

 body of any bird whatever, as well as the shortest feet. The American vultures are likewise 

 of great alar expanse in proportion to their weight. The shortest wings, among birds possess- 

 ing perfect remiges, occur among the lower swimmers, as auks and divers, and among some 

 of the GaUinsB. The great auk is, or was, perhaps the only flightless bird with well-formed 

 flight-feathers, only too small to subserve their usual purpose ; though certain South American 

 ducks are said to be in similar predicament. In the pengfuins, the whole wing-structure is 

 degraded, and the remiges abort in scale-like feathers, the wings being reduced to fins both 



