66 SCOTT. [Vol. V. 



reduced in height, and its distal surface projects but little below 

 that of the magnum. 



The metacarpus is now represented by a cannon-bone, which 

 is as long as, but more slender than in the llama. The lateral 

 metacarpal rudiments have disappeared, unless, as I believe to 

 be the case, the proximal end of mc. II be anchylosed with mc. 

 Ill, forming the projection at the inner side of the cannon-bone. 

 Even in Pcebrotherium there is a tendency for this co-ossification 

 to occur. The fifth metacarpal, on the other hand, appears to 

 have vanished completely. The cleft at the distal end of the 

 cannon-bone is wider and deeper than in the llama, and the 

 articular facets wider. 



The phalanges of the first row only differ from those of the 

 llama " in the greater prominence of the proximal ligamentous 

 insertions and the rather more slender shafts." The unguals 

 are very different from those of Pcebrotherium, being broad, 

 depressed, and flattened with obtuse points ; but they are rela- 

 tively larger than in the recent genera. 



The changes from Procamehis to the existing forms in regard 

 to the structure of the fore limb are not very striking. They 

 consist in an increased robustness of all the shafts, articulations, 

 and ridges for muscular attachment, and naturally to a greater 

 degree in the camel. The most important change is in the 

 proximal end of the humerus, where the external tuberosity is 

 much reduced and the internal tuberosity and the bicipital tuber- 

 cle increased, so that all three are nearly of the same size, and 

 the bicipital groove is much widened. The shaft of the ulna is 

 further reduced, and the olecranon receives a different shape. 

 In the carpus the lunar is reduced in width, and the proximal 

 row of carpals is higher in comparison with the distal row ; the 

 pisiform becomes wider and more compressed. The ungual 

 phalanges are reduced to mere' nodules. 



VI. The Hind Limb. 



The pelvis of Pantolestes is peculiar in many ways. The 

 ilium has a long and very deep peduncle, and a very wide iliac 

 surface. Both the pubic and acetabular borders are raised into 

 arched prominences just in advance of the acetabulum. There 

 is little to suggest that this belongs to an artiodactyl at all. 



