440 University of California Publications in Geology [Vol. 7 



Measurements of No. 19787 





P 3 



M 1 



M 2 



Anteroposterior diameter 



22 mm. 



21.4 



21.6 



Transverse diameter 



23 



22 



20 



Height of crown 



32 + 



32 + 



37 



HIPPABION(?), sp. 



Two moderately worn premolars (no. 19770) representing a 

 Hipparion form somewhat larger than the type of H. mohavense 

 show enamel folds bordering the fossettes in general like those of 

 H. mohavense, but less pronounced and more simple. The 

 difference does not appear to be due entirely to age, and this 

 form may represent a species of Hipparion distinct from H. 

 mohavense. 



A P 2 (no. 19438) may be the same as H. mohavense or may 

 be a distinct species. The enamel plications seem less complex 

 than in H. mohavense and are more acute. 



Measurements 



No. 19770 



P 4 , anteroposterior diameter 25.5 mm. 



P 4 , transverse diameter 24 



P 4 , height of crown 30 



No. 19438 



P 2 , anteroposterior diameter 26 



P : , transverse diameter 20.7 



P 2 , height of crown 30 



PKOTOHTPPUS(?) TANTALUS, n. sp. 



Two large upper cheek-teeth (nos. 19434 and 21221) from 

 the El Paso Range differ from the Hipparion forms in the united 

 protocone and protoconule, curved crown, and large wide fos- 

 settes with crinkling of the enamel limited to their adjacent 

 borders. The outer styles are heavy and narrow noticeably above 

 the base ( figs. 4a and 4& ) . 



These specimens seem certainly different from any referred 

 to Hipparion mohavense or allied species. They possibly repre- 



