278 THE MANUS. [chap. 



is immensely developed ; though its proximal phalanx is 

 extremely short, its ungual phalanx is so long that the 

 entire length of the digit exceeds that of the second. The 

 fourth has a long and rather slender metacarpal, and three 

 phalanges gradually diminishing in size, the ungual phalanx 

 being very small. The fifth has the metacarpal nearly as 

 long, but not so stout as the fourth, and followed by two 

 small phalanges, the last rudimentary and conical, and bear- 

 ing no nail. 



The little Tree Anteater (Cyclothurus didactylus) has a 

 remarkably modified manus. The third digit is greatly 

 developed at the expense of all the others ; it has a stout, 

 short metacarpal, and but two phalanges, of which the most 

 distal is large, compressed, pointed, and much curved, 

 bearing a very strong hook-like claw. The second digit 

 has the same number of phalanges and bears a claw, but 

 is very much more slender than the third. The fourth is 

 represented only by a styliform metacarpal, and there are no 

 traces of either the first or fifth digits of the typical manus. 

 The pisiform is very large. 



In the Armadillos (Dasypodida), the manus is stout and 

 broad, with strongly developed ungual phalanges, adapted 

 for digging and scratching. The fifth metacarpal articulates 

 with the cuneiform as well as the unciform. There is always 

 a very large palmar sesamoid. The digits are almost always 

 five in number, but vary much in relative size and structure. 



In the six-banded Armadillos (genus Dasypus), all the 

 digits have the normal number of phalanges (see Fig. 101). 

 The first digit is rather short and especially slender; the 

 second is the longest, and has all the phalanges, as well as 

 the metacarpal, of nearly equal length ; the third has a long 

 metacarpal, then two short broad phalanges, the first being 

 especially short, and a long, curved, compressed, ungual 



