PERISSODACTYLA. 



ANCHITHERIUM. 



Von Meyer, Jahrbuch fur Mineralogie, 1844, p. 298. 



ANCHITHERIUM ? 



A small calcaneum and astragalus of equine type are pro- 

 visionally referred to this genus until further material enables 

 us to determine them with certainty. 



The astragalus has narrow and very oblique condyles, 

 which are more equal in size than in Orohippus ; the neck is 

 very short, the internal condyle reaching to the face for the 

 navicular ; the posterior projection of this condyle is much 

 shorter than in that genus. The articular face for the navi- 

 cular is quadrate in shape and concave ; the cuboid face is 

 very narrow. The articulation with the calcaneum is made 

 by a narrow, convex face. When the two are in position the 

 navicular face of the astragalus is in the same horizontal line 

 as the cuboid face of the calcaneum, thus resembling the 

 arrangement of the horse's tarsus rather than that of Orohip- 



The calcaneum is a short, slender bone, having the upper 

 and lower margins convergent toward the tuberosity, and 

 not parallel as in Orohippus. The tuberosity is especially 

 small. The face for the cuboid is very narrow. 



From the articular facets of these two bones we can see 

 that the tarsus resembled very much that of the modern 

 horse, with a broad, short navicular, and a narrow cuboid. 

 The strata in which these remains were found were some- 

 what higher than those containing the bones of Orohippus. 



