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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 



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

 epiphyses, 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 metncarpal 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 shm : arm to thigh. The compound metacarpal bone 

 fg hkl bears the "thumb" phalanx z, and the two finger phalanges m, . d' 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 a 1 , or from C to D ; the secondaries on 

 the space $', or from B to C ; the tertiaries upon c 1 ; the scapularies on the upper arra 5 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 



