KiS 



University of California Publications. 



| Geology 



been characterized in any way. so that the nature of the forma- 

 tion is unknown. As geographic location is one of the important 

 factors concerned, the horizon at which this collection was 

 obtained may be referred to under a geographic designation as 

 the Mohave beds. 



The collection presented to the University consists of about 

 one hundred specimens representing teeth, portions of jaws, 

 antlers, and foot-bones. The following forms are represented : 



Merychippus, near calamarius (Cope) 

 Merychippus, sp. indet. 

 Merycodus necatus Leidy 

 Procamelus ( '?) , sp. 

 Pliauchenia ('?), sp. 



The greater number of the horse remains represent a species 

 related to Merychippus calamarius described by Cope from the 

 Santa Fe Upper Miocene. The Mohave form is represented by 

 teeth of a more advanced type than those in the Middle Miocene 

 of the Mascall and Virgin Valley beds. The crowns (pi. 29, figs r 

 la to 36) are longer and somewhat larger in cross-section than 

 any of the forms from the Mascall or Virgin Valley. They are, 

 however, to be included in Merychippus rather than in any of the 

 more advanced genera. 



A worn tooth (pi. 29, fig. 4) in the collection differs enough in 

 dimensions from the other specimens to suggest that it may 

 represent a species, still more advanced than the one just 

 described. It may, however, be included with the other forms. 



A number of astragali (pi. 29, fig. 5) and phalangeal elements 

 of the Merychippus type show considerable differences in size 

 and form, and may represent more than one species. 



The Merycodus remains consist of fragments of antlers evi- 

 dently representing more than a dozen individuals. Several of 

 these specimens are well enough preserved to show the shaft of 

 the horn up to a point above the bifurcation (pi. 29, fig. 7). 

 Other fragments show the terminal portion of the horn (pi. 29, 

 fig. 6). The form represented in these specimens, as shown par- 

 ticularly in plate 29, figure 7, seems identical with that of 

 Merycodus necatus Leidy of the Nebraska Upper Miocene. This 



