1916] 



Merriam: Fauna of Cedar Mountain Region 



181 



APHELOPS?, sp. A 



A large astragalus, no. 19824 (fig. 16), from locality 2026. in 

 Stewart Valley, represents a rhinoceros with a form of tarsus similar 

 to that in Aphelops. This astragalus is near the size and form seen in 

 a specimen from High Rock Canon in northwestern Nevada. 



APHELOPS?, sp. B 



An astragalus, no. 19822 (fig. 17), with an anteroposterior diameter 

 about one half that of no. 19824, seems to represent another rhinoceros 

 possibly near the Aphelops type. This specimen is similar in size and 

 form to a specimen 1201 from locality 871, presumably from the 

 Upper John Day Oligocene of the eastern Oregon. The cuboid facet 

 is a little large and is flatter at the lower end in the Cedar Mountain 

 specimen. The inner facet for the astragalus is considerably smaller 

 in the Cedar Mountain specimen. 



Equidae 



Remains of horses are relatively rare in the Cedar Mountain beds, 

 and only a very few teeth and isolated limb-bones have been obtained. 

 Judging by the relative quantity of remains, the horse fauna seems 

 to have been overshadowed in importance by the camels in this region 

 during deposition of the Cedar Mountain beds. 



The forms known thus far include Hypohippus (Drymohippus) 

 nevaclensis, a species near Hypohippus osborni but possibly identical 

 with the first-mentioned form, a Meryehippus species near the M. 

 calamarius forms of the Barstow fauna, and a few fragments indicat- 

 ing the presence of a form more advanced than the common species 

 of the Barstow. This last form may be comparable to the most 

 advanced type of the Barstow resembling Protohippus or Pliohippus 

 and rarely seen in that fauna. 



It is perhaps significant that the browsing type, Hypohippus or 

 Drymoh ippus, plays a relatively important part in the Cedar Mountain 

 fauna as it is known at this time. If horses are relatively rare in 

 Miocene deposits in which ungulates are fairly represented, and if 

 the Hypohippus type represents a relatively large percentage of the 

 horses present, one unavoidably considers the possible influence of 

 environment in determining range and representation of the group. 

 Absence of grazing horses, as Meryehippus, and presence of browsing 

 forms would be due to absence of grass or to predominance of brush. 



