282 THE AIANUS. [chap. xvi. 



first and fifih digits ; while the second, third, and fourth 

 remain functional, with long ungual phalanges cleft me- 

 sially at their extremities. The third is longer than the 

 second, and this longer than the fourth. In Chteropiis the 

 second and third remain, and retain their relative size, 

 though comparatively longer, more slender, and with smaller 

 ungual phalanges. The fourth digit is rudimentary, but 

 with the normal number of phalanges ; the first and fifth 

 are entirely suppressed. The carpal bones have their 

 normal relations, but the trapezium is exceedingly reduced. 



Order Monotremata. — In the Echidna the carpus is 

 short and broad, and has a very complex articulation 

 with the distal ends of the radius and ulna. The first row 

 consists of a scapho-lunar and a cuneiform. There is no 

 central. The distal row has the usual four bones. The 

 pisiform is large, and articulates with the ulna as well as the 

 cuneiform, and there is a small radial sesamoid, articulating 

 with the scapho-lunar. There are also two large sesamoids, 

 sometimes united, in the palmar tendons. The digits are 

 five in number, all with the normal number of phalanges, 

 which are short and broad, except those that bear the 

 long, slightly curved, broad nails, with which the animal 

 scratches and burrows in the ground. The pollex is more 

 slender than the other digits ; it is of about the same length 

 as the fifth, the second and fourth are nearly equal and 

 longer, and the third slightly the longest. 



In the Ornithorhynchus the manus is comparatively more 

 slender and elongated ; but the number and arrangement 

 of the bones are the same as in the Echidna. 



