[PERISSODACTYLA.]
ANCHITHERIUM.
Von Meyer, Jahrbuch für Mineralogie, 1844, p. 298.
Anchitherium —— ?
A small calcaneum and astragalus of equine type are provisionally 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 navicular 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 Orohippus.
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 somewhat higher than those containing the bones of Orohippus.