198 DINOCERATA. 



maxillaiy protuberances are well developed, divergent, and connected by 

 a moderate ridge. The top of the skull beliind this is flattened, and 

 separated from the lateral surface by a more or less prominent ridge, 

 rising well on the front surface of the elevated parietal processes. These 

 processes are over the post-glenoid processes. They are high, and, 

 toward the apex, flattened antero-posteriorly, while they expand in 

 transverse diameter. The ridge connecting them across the surface of the 

 skidl is present, but not elevated. 



The foramen magnum is slightly higher than the occipital condyles. 

 The palate is excavated in the region of the diastema. 



Figure 111. — Skull of Dinnceras miiieum, Marsh (No. 1042); seen from above. 



One-eiglitli natural size. 



Another specimen (number 1207, figure 170) has the s^iout very 

 tapering in front, and the nasal protuberances small, though rather 

 prominent. The median suture is entirely obliterated, and the prenasals, 

 if present, are thoroughly co-ossified with each other, and with the nasal 

 bones. 



The maxillary prominences are rounded, and not very divergent. 

 The parietal protuberances are connected l)y a transverse ridge. The 

 zygomatic process of the squamosal is not excavated for the posterior 

 end of the malar. 



The type specimen (number 1042) of this species was secured in May, 

 1875, by Messrs. S. Smith and J. Heisey, near Haystack Mountain, 

 about sixty-five miles east of Green River, Wyoming. 



The specimen consists of a skull, with a nearly complete series of 

 dorso-lumbar vertebne, sacrum, pelvis, etc. 



The second specimen (number 1207), consisting of ])ortions of the 

 skull and vertebrae, was found by J. W. Chew and the author, in 187o, 

 near Big lione Buttes, Wyoming. 



The geological horizon is in the Bridger beds of the I\riddle Eocene. 



The only known specimens are in the Yale Museum. 



