DINOCEEATA, 



CHAPTER I. 



THE SKULL. 



(Plates I-XIX, LV, and LVI.) 



The skull of Binoceras mirahile, the type of the genus Dinoceras, on 

 which the order Dinocerata was based, is, fortunately, the most perfect in 

 preservation of any yet discovered in this group. It has in addition the 

 great advantage for study of having belonged to an animal fully adult, but 

 not so old as to have the more important sutures of the skull obliterated. 

 It was, moreover, imbedded in so soft a matrix that the brain-cavity and 

 the foramina leading from it could be worked out without difficulty. 



In removing the skull from the rock, on the high and almost 

 inaccessible cliff where it was found, two or three important fragments 

 were lost, but the author subsequently made a systematic and laborious 

 search, and recovered them from the bottom of a deep ravine where they 

 had been washed down and covered up. 



In its present nearly perfect condition, this skull is well adapted to 

 show the typical characters of this part, both in the genus it represents, 

 and in the order Dinocerata. and it will be largely used for this purpose iu 

 the following pages. The fact that a considerable portion of the skeleton, 

 also, was found with this skull makes the individual especially worthy to 

 be a type. - 



