EXTERNAL PARTS OF BIRDS. — THE WINGS. 117 



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 icing. 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 below," or " under surface of the 

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

 coverts in general, the axiUars, or axillary feathers (Lat. axilla, 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 axillaries is the 

 principal distinction between some species of plovers. The 



Remiges, or Flight- Feathers (fig. 30, b, s, and f),give 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 

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

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

 liumming-bird, for example, very short in ct)mparison with the terminal portion of the limb, 

 and in an albatross again, both upper and forearm being greatly lengthened ; still in any case 

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

 (if 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 bone and muscle lie, thence growing more mobile and resilient toward the 

 posterior border and along the outer edge. Such surface may be quite fiat, 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 wing 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 wing-beats ; birds of this style of wing are generally trim and elegant. These, 

 of course, are merely generahzations of the extremes of modes of flight, mixed and gradated 

 ill every degree in actual bird-life. Thus the humming-bird, which has sharp, 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- 

 r.ess and concavo-convexity is a remai'kably strong one, confcmug a rapid, vigorous, whistling 

 flight, as that of a duck or pigeon, or the splendid hurtling of a fiilcon. An ample wing, as 

 one both long and broad without being pointed is called, is Avell 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 fiiund among the swimmers, particularly the pelagic 

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

 pelican. The last named, Tachypetes 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 Gallinse. 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 penguins, the whole wing-structure is 

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



