252 0. C. Marsh—Notice of New Tertiary Mammals. 
The known remains of this species indicate an animal about 
two and a half feet in height. The specimens described are 
from the Pliocene beds at Antelope Station, Nebraska. Other. 
remains of the same species were found by the writer, last year, 
. 
on the Niobrara River, in the same geological horizon. 
Pliohippus pernix, gen. et sp. nov. 
A new genus of solipeds, allied to Hyuus, is well represented 
in the Yale Museum by two partial skeletons, with the more 
important portions preserved, and by numerous fragmentary 
remains. This genus closely resembles Protohippus Leidy in 
its dentition, but differs in the absence of lateral digits, which 
are only represented by slender splint bones. From the true 
Equus, the present genus may be distinguished by the presence 
of a large antorbital fossa; by the functional first upper pre- 
molar; and a different composition of the crowns of the 
upper molars. The dental formula of Pliohippus is as follows: 
. 3 1 4 3 
Incisors =, canines —, premolars —, molars =. 
3 1 ee 3 
The incisors have the characteristic pit of the modern horse. 
The molars have short crowns, with distinct fangs. The skull 
ulna is not entire, and its extremities are ankylosed to the 
radius. The distal end of the fibula has coalesced with the 
tibia. On the radial side of the carpus, there is a small ossicle 
which appears to represent the trapezium. On the opposite 
side, attached to the unciform, there was a rudiment of the 
the inner lobes. The limbs were slender, and more elongated 
n in the ass. The ungual phalanges are broader, and 
slightly cleft at their extremities. The femur has the fossa 
above its outer condyle unusually deep. The cuboid facet 00 
the astragalus is larger than in most equines. 
Measurements. as 
Extent of four upper premolars, Be ee 5 eM 
Antero-posterior diameter of first upper premolar, ---- - 13° 
Antero-posterior diameter of second premolar, - --- --- -- +1 
Extent of three upper true molars, -__-_._- ee 63° 
Ante erior diameter of last upper molar,----- --- 8° 
Extent of lower mollis See. 3 = 146° 
Extent of last three lower molars,._........----.---- 72. 
' ep ae oe 
