0. C. Marsh—Notice of New Tertiary Mammals. 249 
The animals of this genus constitute a distinct family that 
may be called Orohippide. The other known species are as 
follows : : 
_ Orohippus gracilis Marsh. 
(Anchitherium gracile Marsh ;) this Journal, ii, p. 38, 1871. 
Orohippus pumilus Marsh. 
This Journal, iv, p. 207, 1872. (? Helotheriwm procyoninum Cope, Proc. Am. Phil. 
Soe., xii, p. 466, Feb., 1873.) 
Orohippus agilis Marsh. 
This Journal, v, p. 407, 1873. 
All the animals of this genus now known were quite dimin- 
utive, the largest hardly exceeding a fox in size. They are all 
from the Eocene of Wyoming and Utah. 
Miohippus annectens, gen. et sp. nov. 
The present genus represents an intermediate form between 
Orohippus and Anchitherium. It differs from the former in 
having but three digits in the manus, and from the latter in the 
absence of an antorbital fossa, and in the more complete sepa- 
the manus, and three in the es, all of which reached the 
sround. They appear to have tee more nearly of equal size 
than in Anchitherium. ; : 
_4n the present species the orbit is large, and its anterior mar- 
10 1s directly above the front of the last upper molar. 
rst upper premolar had two fangs. The enamel of all the 
teeth preserved is quite smooth. The upper premolars and 
* Proc. Acad. Nat. Sci. Philadelphia, 1870, p. 112. 
