214 



Reiieics — Prof. 0. C. Marsh's Dinocerata. 



{Paraxnnia) ; in others they avelike the PerissodadyJa^ (Mesaxonia) ; 

 and in others still, they agree with the Proboscidians.^ The 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 TJintatherhm, 

 Leidy. The type specimen of Uintatherium was discovered near the 

 base of the series of strata containing the remains of the Dinocerata. 

 Dinoceras, so far as known, occurs only at a higher horizon, while 

 Tinoceras has been found at the highest level of all. The characters 



Fig. 1.— Skull of Dinoceras miraUle, Marsh (seen from the left side). One-sixth 

 natural size. From the Eocene Tertiary Lacustrine deposits of Wyoming 

 Territory, United States, North America. 



of these three genera correspond in general with their geological 

 position. Uintatherium appears to be the most primitive type, and 

 Tinoceras the most specialized, Dinoceras being an intermediate form. 



" About thirty species of Dinocerata, more or less distinct, are 

 recognized by the author in the Synopsis at the end of the volume. 



" The Skull. — The skull of Dinoceras mirabile is long and narrow, 

 the facial portion being greatly produced. The basal line, extending 



1 Ferissodactyla, or uneven-toed (Horse, Tapir, Rhiuoceros). 

 '^ Frohoscidia (Elephant, Mastodon, JJiuotherium). 



