314 PROCEEDINGS OF THE NATIONAL MUSEUM vol.83 



species examined. The distal portion, however, appears relatively 

 deep anteroposteriorly as compared with E. grevyi. The distal portion 

 is deep relative to its width in comparison with E. caballus, although 

 the keel is less outstanding. 



The sphnt bones are robust proximally, particularly the outer, 

 and the length where complete is variable but apparently averaging 

 somewhat longer than in recent material. They taper or flatten dis- 

 tally and may be slightly expanded at the end but the enlargement is 

 not so pronounced as in some recent horses. The second metatarsal 

 usually shows a facet of variable size for articulation with the external 

 cuneiform. 



The proximal sesamoids articulating with the distal surface of the 

 third metatarsal are smaller than in the front foot, and as in the latter 

 are relatively narrower than in E. caballus. 



Posterior phalanges. — The phalanges of the hind foot (fig. 24, B), as 

 in the fore foot, are much narrower than in E. caballus and more 

 closely approach the proportions seen in E. grevyi. There is little 

 difficulty in distinguishing between phalanges of the fore and hind 

 foot of one individual but with isolated toe bones identification is often 

 uncertain. The first phalanx of the hind foot is a little shorter, the 

 proximal end a little heavier, and the distal end narrower. The second 

 phalanx is narrower and perhaps a little longer. The hoof is some- 

 what narrower, and the anterior margin though not pointed is less 

 rounded than in the fore foot. The right and left sides may be dis- 

 tinguished by the slight asymmetry of the elements, very readily 

 in the first phalanx but not so easily in the distal element. 



