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GENERAL DEFINITIONS. 



The Wing. The wing of a bird represents the fore 

 limb of a quadruped, or the arm of man, modified 

 for flight in a very remarkable manner. It joins the 

 body by a shoulder-joint ; thence a single long bone, 

 the humerus, extends to the elbow, whence a pair of 

 bones, the ulna and radius, reach to the wrist. There 

 are some small bones in the wrist-joint, and the limb 



B 



FIG. 5. BONES OF A BIRD'S WING. (Taken from a young chicken, in which the 

 epiphytes, or caps of growing bone, are still separate from the shafts.) A, shoul- 

 der. B, elbow. C, wrist, or carpus, sometimes loosely called ''shoulder." E, junc- 

 ture of metacarpal bones of hand with phalanges of the finger. D, tip of principal 

 finger. A to B, arm, or upper arm, represented by a, the humerus. B to C, fore- 

 arm, represented by b, the ulna, and c, the radius, d and e, the two carpal or wrist- 

 bones {radial and ulnar). The figure 1 indicates lines running to the epiphyses of the 

 humerus ; the ends of ulna and radius show similar epiphyses, separated by zigzag 

 lines from the shafts of these bones ; g and f are similarly the epiphyses of the two 

 principal metacarpal bones ; k, the third, and /, the fourth, h is the second metacarpal 

 bone (there is no first metacarpal in birds), h, k, and / soon fuse together, making a 

 single compound metacarpal bone, corresponding to the metatarsal bone ("tarsus") of 

 the foot ; the ulna and radius correspond to the tibia and fibula of the leg ; the hume- 

 rus to the femur ; forearm to shin ; arm to thigh. The compound metacarpal bone 

 fg hkl bears the "thumb" phalanx i, and the two finger phalanges m, n. d 1 is 

 the first finger or "thumb," bearing the alula, or "bastard wing." d" is the next 

 finger, and there may be another, not represented. The " primaries " are those feath- 

 ers that grow on the space marked by the lines ', or from C to D ; the secondaries on 

 the space b', or from B to C ; the tertiaries upon c'; the scapularies on the upper arm, a". 



is finished by several bones of the hand, including 

 those of the fingers. Just as in the case of the leg, the 

 bones and joints correspond completely with those of a 



