56 DINOC'EHATA. 



The cribriform plate, bounclin<<' these lobes in front, is thin and easily 

 displaced, but its position in the specimen is shown approximately by the 

 extremity of the olfactory lobes represented in Plate VI. In front of this 

 plate the olfactory nerves were spread ont in a large cavity, which is 

 represented in figures 30 and 31, page 29. The nasal canals extend 

 forward from this cavity to the external nares, as indicated in the .same 

 figures. In these canals there were thin, well developed, ethmo-turbinal 

 bones, which were easily displaced, and l)roken uji. The presence of 

 these bones is strong evidence that there was no pi'oboscis. 



The optic nerves, or second pair, were well developed. Their 

 position, size, and place of exit, are shown in Plate VI, figure 3, op. 



The fifth pair of nerves, or tri-geminals, were very large, and Avere 

 given off on either side, behind the optics, and opposite the depression for 

 the pituitary body, as shown in Plate VI, figure 3, v. 



The sixth pair of nerves passed off immediately behind and below the 

 last pair. Their position and relative size are shown in Plate VI, figure 

 3, / The twelfth pair, or hj^poglossal nei'ves, passing off through tJie 

 condylar foramina, were large, and their ])osition is given in Plate VI, 

 figure 3, XII, and cf. The position and exit of the other nerves sent off 

 from the brain cannot be determined with certainty. 



In the genus Thtocerns, the brain was similar in its general characters 

 to that of Dinoceras, but appears to have been somewhat more highly 

 developed, as shown in figures 59 and (!0, i)age 55. The hemispheres 

 were more elongate, and the olfactor}- l()])es relatively smaller. The 

 cavities for the flocculi were quite large, and directed well fi)rwai'd. 

 The twelfth pair of nerves were largely developed. 



In Uintatlierhim, the brain of the type specimen was nearly, or quite, 

 as small as in Dinoceras. The hemispheres were short, and moderately 

 expanded transversely. The olfactory lobes were separated by a wide 

 septum, and were much more divergent than in Dinoceras or Tinoceras. 

 These characters are shown in figures 61 and 62, page 57, which are of 

 the same relative size as the fiirures in Plnte VI. 



