294 



University of California Publications. [Geology 



andrae. It may be referred to the genus Ilingoceros, though it 

 is not entirely certain that it is not also generically different. 



The form of horn represented in this specimen suggests rela- 

 tionship with three groups, the Merycodontidae, the Antilo- 

 pinae and the Antilocapridae. The resemblance to any known 

 form of the Merycodus group is not close. The burr is entirely 

 absent, the horn-core is strongly twisted, and the distal notching 

 is very shallow. The shallowness of the notch might be expected 

 in a young individual. There is, however, some reason for sus- 

 pecting that this horn may represent a full grown animal, as it 

 is associated with numerous remains of small antelope-like ani- 

 mals which are evidently adults. The horns of Merycodus 

 nevadensis from the Virgin Valley Beds at High Rock Canon 

 present as near an approach to the antelope form as has been 

 observed among forms referred to Merycodus. 



The resemblance of this form to true antelopes of the strepsi- 

 cerine type has already been commented upon in a former publi- 

 cation. 29 With only the portion of the horn below the tip repre- 

 sented a relationship to the tragelaphines is unavoidably sug- 

 gested. Considered in connection with the other forms referred 

 originally to the genus Ilingoceros, there seems good reason for 

 inquiring whether this resemblance is not more than coinci- 

 dence. There are no other horned forms in which the strepsi- 

 cerine characters are developed, and the twisted-horned ante- 

 lopes have been quite conspicuously represented in Tertiary 

 time, their origin dating back at least to the Miocene period. 

 Inasmuch as the antelope group has been presumed to be derived 

 from forms near Merycodus it would not seem improbable that 

 types like /. schizoceras should appear in the period of transition 

 to the true strepsicerine forms, and possibly also in the young of 

 early representatives of that group. 



The resemblance of the horn-core of this form to that in 

 Antilocapra consists largely in the general similarity of the sur- 

 face structure. The form and position of the horn are not like 

 those of the pronghorns, and the nature of the terminal region 

 is also distinctly different. The fact that this horn-core is divided 



"'■> Merriam, J. C, op. cit. 



