218 DINOCERATA. 



The palate is excavated in tliu region of the diastema, and the 

 palato-maxillaiy foramen is just in front of the first premolar, but not 

 so far in front as in Tinoceras ingeiis (number 1041). 



The lower ]a\v is slender, and expands rapidly in the region of the 

 symphysis for the formation of the flanges protecting the canine tusks. 

 When seen from a'nove, the angle at which the rami meet at the 

 symphysis is distinctly rounded in front, tluiugh somewhat less strongly 

 than in Dinoceras hiticeps (Plate XII, figure 1). 



The type sjiecimen (number 15G7) of this species was collected by 

 Mr. S. Smith, at Haystack Mountain, Wyoming, in May, 1882. 



The remains of tliis specimen consist of a skull, with lower jaw, etc. 



The geological li(_)rizon of this species is in the Dinocei-as beds of the 

 Middle Eocene. 



The known remains of this species are in the """ale College Museum. 



TiiKK-eras yniians, iVlarsh. 



Wu.jikut: I-', \K K. 

 Marsh, Fifth Annual Report of the U. S. Geoloc;ieal Survey, (figure from the present 

 volume, viz:) fig. 49, p. 262, 1884. 



The snout in tlic ivyo id' this species (inmd:ier 1241) tapers somewhat 

 in front, and the nasal protuberances are flattened and directed forward, 

 outward, and upward. The nasal bones are vmited throughout. The 

 maxillar}' protidjerances are slender, Ijut prominent, and united across by 

 a low rounded ridge. The ujjper surface of the skull is separated from 

 the lateral surface, above and liehind the orbits, by a ridge, which rises 

 upon the parietal protuberances. These are prominent, and are flattened 

 antero-posteriorly. The}' Axere connected across the top of the skull by 

 a low transverse elevation. 



The type specimen (number 1241) of this species was discovered by 

 Mr. S. Pearson, at Red Dog Buttes, Wyoming, in July, 1875. 



This specimen consists of ])ortions of tlie skull, etc. 



The geological horizon is in the Dinoceras beds of the Middle Eocene. 



The known remains of this species are preserved in the Yale Museum. 



