34 THE STORY OF THE BIRDS 



the Metacarpus or space between the wrist and 

 the digits, and the Digits or fingers, the three 

 sets together forming the hand. The first and 

 shortest of the three metacarpals (together 

 forming the metacarpus) bears the thumb or 

 Pollex (to the basal joint of which the bastard 

 wing is attached), consisting of one or two 

 joints (the terminal one frequently absent or 

 aborted) ; the second and strongest composed 

 of two or three joints is termed the Index ; 

 whilst the third, the weakest and most slender, 

 has one joint only. Some few Archaic birds 

 (Ratitae) possess the second metacarpal only ; 

 whilst in the Penguins it is fused with the first. 

 Claws at the tips of the metacarpals are rare 

 in existing birds, although as we have already 

 seen the extinct Archaeopteryx was provided 

 with them. In modern birds they apparently 

 mostly appear accidentally upon the thumb and 

 index, and probably in no case are functional. 

 We have seen a pollex claw upon the Common 

 Whitethroat, and such is found in various 

 Anserine birds, in the fowl, and in some 

 Raptorial birds. Conical spurs are not un- 

 common on the carpal and metacarpal bones, 

 and are often used as weapons. 



The bones of the legs or posterior limbs, like 



