178 Professor Marsh's Monograph of the Dinocerata. 
“The Dinocerata form a well marked order in the great 
group of Ungulata. In some of their characters, they résem- 
ble the Artiodactyls (Parawonta); in others they are like the 
Perissodactyls wba and in others still, they agree 
with the Prcbossidinhe. he points of similarity, however, 
are in most cases general characters, which point back to an 
earlier, primitive ungulate, rather than indicate a near affinity 
with existing forms of these groups. 
“The Dinocerata, so far as now definitely known, may be 
placed in three genera, Dinoceras, Marsh, Tinoceras, Marsh 
and Uintatherium, Leidy. The type specimen of Uintathe- 
rium was discovered near the base of the series of strata con- 
taining the remains of the Dinocerata. Dinoceras, so far as 
known, occurs only at a higher horizon, while Zinoceras has 
been found at the highest level of all. The characters of these 
three genera correspond in general with their geological posi- 
tion. Uintatherium appears to be the most primitive type, 
and T%inoceras the most specialized, Dinoceras being an inter- 
mediate form. 
“The number of species of the known Dinocerata is a diff- 
cult matter to determine, especially as the limitations between 
species are now generally regarded as uncertain. About thirty 
forms, more or less distinct, are recognized in the Synopsis at 
the end of the volume. 
Tue SKvLt. 
“The skull of Dinoceras mirabile is long and narrow, th 
e 
facial portion being poxty produced. The basal line, extend- 
ing from the end of the premaxillaries along the palate to the 
lower margin of the foramen magnum, is nearly straight. — The 
top of the skull supports three, separate, transverse pairs 0 
s elevations, or horn-cores, which form its most con 
spicuous feature, and suggested the name of the genus. The 
smallest of these protuberances are situated near the ou 
of the nasals ; two others, much larger, arise from the maxl> 
laries, in front of the orbits; while the largest are nail 
the parietals, and are supported by an enormous crest, W ch 
extends from near the orbits entirely around the lateral and 
posterior margins of the true cranium. These general ¢ a 
ters are well shown in figure 2, which represents the skull 0 
the type specimen. 
“There are no upper incisors, but the canines in the — | 
are enormously developed, forming sharp, trenchant, decurv 
tusks, which were each protected by a dependent process iL 
the lower jaw. The premolar and molar teeth are very 8” 
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