24 



Measurements. 



M. 



Greatest length of astragalus o-02i 



Greatest breadth of ditto -oiS 



Length of neck of ditto -005 



Width between the condyles -oio 



Vertical diameter of face for navicular -012 



Tranverse diameter of ditto -012 



Length of calcaneum -046 



Width of face for cuboid .,,...... -006 



From Henry's Fork. 



OROHIPPUS, Marsh. 



Am. Jour. Sc. vol iv., p. 207, third series. 



Generic Cliaractcristies. — " The crowns of the upper true 

 molars are composed of a pair of external cusps similar to 

 those of anchitherium. There are two coresponding inner 

 tubercles, from which ridges extend obliquely to the anterior 

 inner margin of the outer cusps ; but the anterior ridge is 

 divided so as to form an intermediate anterior tubercle. All 

 the teeth preserved have a distinct basal ridge." 



Species Knoivn. — 



Orohippus pumilus, Marsh. 

 Orohippus major. Marsh. 

 Orohippus agilis, Marsh. 

 Orohippus gracilis, Marsh. 



Orohippus pumilus? Marsh. 



Specimen obtained. Penultimate and third superior mo- 

 lars, with part of zygoma. 

 From CottonwoodCreek. 



Orohippus major? Marsh. 



Femur (Plate IX., Fig. i). — The femur has a small, nearly 

 hemispherical head, developed on a long and slender neck ; 

 the head is but slightly out of the axis of the shaft, and has a 

 large pit for ligamentous insertion. The shaft is long, simple, 

 and curved slightly forward. At the proximal end it is 

 broad and flattened axially ; below this it becomes expanded 

 fore and aft, but it thickens greatly at the distal end, just 



