112 



GENERAL ORNITHOLOGY. 



and by compression of those that are left, as more particularly said beyond. The wing 

 proper begins at the shoulder-joint, where it hinges freely in a shallow socket formed con- 



^ ^ /(^^^V\ jointly by the shoulder- 



-^— ^T/j /^^\\>r\ blade or scopztZa, and by the 



?^^>j^ Vk VVV^' ^(^^'^^oid ; these two bones, 



^ with the clavicles, collar- 



bones or merry - thought 

 (furculum) forming the 

 shoulder-girdle, or pectoral 

 arch (figs. 56, 59). 



The wing ordinarily 

 consists, in adult life, of 

 teyi or eleven actually sepa- 

 rate bones ; in embryos (see 

 fig. 29) there are indications 

 of several more at the wrist 

 (carpus), which speedily 

 lose their identity by fusing 

 together and with bones 

 of the hand (metacarptis) . 

 Aside from these, there is 

 often an accessory ossicle 



^^, upper arm, brachlum ; £ C, foTe-arm, antibrachium ; C'Z», whole hand at the shoulder -joint (fig. 



56, ohs), sometimes one at 

 the wrist-joint, occasionally 

 an extra bone at the end of 

 the principal finger. Among 

 RatittB, the carpal bones 

 are reduced to one in a Cas- 

 sowary, to none in an Emeu 

 and a Kiwi; all of which 

 birds have but a single digit. 

 The Archceopteryx had the 



Fig. 27. — Bones of right wing of a duck, Clangula islandica, from above, 

 nat. size. (Dr. R. W. Shufeldt, U.S.A. ) A, shoulder, oinos ; B, elbow, ancon; 

 C, wrist, carpus ; I>, end of i)rineipal finger ; E, end of hand proper, metacarpu. 



or pinion, maniis; composed of CE, hand proper or metacarpus, excepting d '■ 

 ED,OT d - d 3, d *, fingers, digits, digit i. h, humerus ; rd, radius ; ul, ulna ; sc, 

 outer carpal, scapholunare or radiate ; cm, inner carpal, cuneiforme or ulnare; 

 these two composing wrist or carpus, mc, the compound hand-bone, or meta- 

 carpus, composed of three metacarpal bones, bearing as many digits — the outer 

 digit seated upon a protuberance at the head of the metacarpal, the other two 

 situated at the end of the bone, d 2, the outer or radial digit, commonly called 

 the thumb or pollex, composed of two phalanges ; d^, the middle digit, of two 

 phalanges; d*, the inner or ulnar digit, of one phalanx d- is the seat of the 

 feathers of the bastard icing or alula. L> to T' (whole pinion), seat of the flight- 

 feathers called primaries ; C to B (fore-arm), seat of the secondaries ; at B and 

 above it in direction of vl, seat of tertiaries proper; below A, in direction of iJ, 

 seat of scapidaries (upon pteryla humeralis), often called tertiaries The wing 

 shown half-spread: complete extension would bring ABC D into a right line; 

 in complete folding C goes to A, and Z> to B ; all these motions nearly in the 

 plane of the paper. The elbow-joint and wrist are such perfect hinges, that, in most bones of any known 

 opening or closing the wing, C cannot sink below the paper, nor D fly up above -i . i • V, +V, 



the paper, as would otherwise be the effect of the pressure of the air upon the ''1™, With three separate 

 flight-feathers. Observe also : r(/ and m/ are two rods connecting iJ and C; the metacarpals, three free di- 

 constructionoftheirjointing at i} and r, and with each other, is such, that they . rl It tV. 



can slide lengthwise a little upon each other. Now when the point C, revolving S"^' ^"'^ altogether nine 

 about B, approaches A in the arc of a circle, rd pushes on sc, while id pulls back phalanges. The normal or 

 cu ; the motion is transmitted to D. and makes this point approach B. Con- 1 ^ f ■ ^ 



versely, in opening the wing, rd pulls back .sc, and ul pushes on cu, making D ^^"^^ numoer OI wmg-Dones 

 recede from 5. In other words, the angle j1 7J C cannot be increased or dimin- is shown in fig. 27, taken 

 ished without similarly increasing or diminishing the angle £ C 7); so that no f,.^,„ „ J„„i, ( rifitmuln 

 part of the wing can be opened or shut without automatically opening or shut- "*"" ^ °_ \,vmngiaa 



ting the rest,— an interesting mechanism by which muscular power is corre- islandica), in 

 lated and economized. This latter mechanism is further illustrated in fig. 28, 

 where re and mc show respectively the size, shape and position of the radial con- 

 dyle and ulnar condyle of the humerus. It is evident that in the flexed state of 

 the elbow, as shown in the middle figure, the radius, rd, is so pushed upon that 

 its end projects beyond ul, the ulna ; while in the opposite condition of extension, 

 shown in the lower figure, rd is pulled back to a corresponding extent, 

 which alone forms the first segment of the wing. In the closed wing, the humerus lies nearly 

 in the position of the same bone in man when the elbow is against the body ; in extension 

 of the wing, the elbow is borne away from the body, as when we raise the arm, but carry it 

 neither forward nor backward. A peculiarity of the bird's humerus is, that it is rotated on its 



which there 

 are eleven. 



The upper arm-bone, 

 h, reaching from shoulder A 

 to elbow B, is the humerus, 



