554 University of California Publications in Geology [Voi*. 11 



Measurements of no. 21311 



P 2 , anteroposterior diameter 29.9 mm. 



P 2 , transverse diameter 20.2 



P 3 , anteroposterior diameter 27.4 



P 3 , transverse diameter 23.2 



P 4 , anteroposterior diameter 24.8 



P 4 , transverse diameter 21.5 



P 4 , height of mesostyle 45.5 



M 1 , anteroposterior diameter 24.5 



M 1 , transverse diameter 22.6 



M 2 , anteroposterior diameter 24 



M 2 , transverse diameter 20.4 



M 2 , height of mesostyle 41 



M 3 , anteroposterior diameter 21 



M 3 , transverse diameter 18 



P., Anteroposterior diameter 28.4 



P 2 , greatest transverse diameter 12 



P 3 , anteroposterior diameter 27 



P 3 , greatest transverse diameter 13.7 



P 4 , anteroposterior diameter 27.4 



P 4 , greatest transverse diameter 13 



P 4 , height of protoconid 51 



M„ anteroposterior diameter 25.8 



M„ greatest transverse diameter... 11.4 



M ; , anteroposterior diameter 27.3 



Mo, greatest transverse diameter 10.8 



M 2 , height of protoconid 44.4 



M s , height of protoconid 44.4 



M : „ greatest transverse diameter 10.4 



HIPPAKION, sp. A 



A very large Hipparion P' J , no. 22303 (fig. 176), found in the 

 Ricardo beds between the uppermost and the second basalt flows 

 differs so much from the typical H. mohavense in its large size that 

 it may represent a distinct species. The pattern of the enamel sug- 

 gests in some respect the Hipparion mohavense callodonte form. 



Measurements of no. 22303 



P 2 , anteroposterior diameter 35.6 mm. 



P 2 , transverse diameter 22.8 



HIPPAEION, sp. B 



In the collection of Professor James Perrin Smith of Stanford 

 University there is a M 2 (fig. 177) of a Hipparion from the upper 

 portion of the Ricardo. This tooth is much narrower than M 2 of the 

 type specimen of H. mohavense, while the enamel folds are less com- 



