0. C. Marsh—Mammals of the order Dinocerata. 119 
gular group of animals, and the more important characters are 
here mentioned, preliminary to the full description. Most of 
the cranial characters are derived from a very perfect skull of 
Dinoceras mirabilis, figured in the accompaning plates. 
e skull is unusually long and narrow. The three pairs of 
horn cores, rising successively above each other, and the huge 
the orbit. These posterior horn-cores are higher than those in 
front, and have obtuse summits, flattened transversely. (Plates 
L-IL) The frontal bones have no postorbital process, and the 
orbit is not separated from the temporal fossa. The latter is 
very large posteriorly. (Pl. II, fig. 1.) The squamosal forms 
the lower portion of ‘the temporal fossa, and sends down a mas- 
the orbit, the frontal sends out laterally a prominent ridge, 
which afforded good protection to the eye in the combats of 
Separated externally, and meeti D ‘ 
he asals oman oe gaa prolonged anteriorly. In 
