488 MANUAL' OF ZOOLOGY. 



expansion of the wing ; the hand is thus fixed in a state of 

 pronation ; all power of flexion, extension, or of rotation, is 

 removed from the wrist-joint, so that the wing strikes firmly, 

 and with the full force of the contraction of the depressor 

 muscles, upon the resisting air " (Owen). One other bone 

 of the normal carpus (namely, the " os magnum ") is present, 

 but this is anchylosed with one of the metacarpals. There 

 are thus really three carpal bones, though only two appear 

 to be present. The carpus is followed by the metacarpus, 

 the condition of which agrees with that of the carpal bones. 



Fig. 213. Fore-limb of the Jer-falcon. h Humerus ; r Radius ; u Ulna ; / " Thumb ; " 

 m Metacarpals, anchylosed at their extremities ; //Phalanges of fingers. 



The two outermost of the normal five metacarpals are absent, 

 and the remaining three are anchylosed together with the 

 os magnum so as to form a single bone (fig. 213, m). This 

 bone, however, appears externally as if formed of two meta- 

 carpals united to one another at their extremities, but free 

 in their median portion. The metacarpal bone which cor- 

 responds to the radius is always the larger of the two (as 

 being really composed of two metacarpals), and it carries 

 the digit which has the greatest number of phalanges. This 

 digit corresponds with the "index" finger, and it is com- 



