1919] Merriam: Tertiary Mammalian Faunas of Mohave Desert 551 



on the inner wall opposite the protocone. The type specimen was 

 found to differ from Hipparion richthofeni of China in the presence 

 of a single fold in the enamel wall opposite the protocone, while in 

 H. richthofeni a double fold may appear at this point. In the speci- 

 men no. 21320 the fold may be double as in H. richthofeni. 



168a 168b 16 g 



Figs. 168a and 1686. Hipparion mohavense Merriam. Inferior cheek-teeth 

 associated with type specimen, no. 19787 '?, natural size. Fig. 168a, P 4 ; Fig. 1685, 

 P.. Eicardo Pliocene, Mohave Desert, California. 



Fig. 169. Hipparion mohavense Merriam. M 2 , no. 21209, natural size. Eicardo 

 Pliocene, Mohave Desert, California. 



Figs. 170a and 170b. Hipparion mohavense Merriam. Lower cheek-teeth, 

 no. 21348, natural size. Fig. 170a, P 2 ; fig. 1706, P 4 to M,. Eicardo Pliocene, 

 Mohave Desert, California. 



Several lower cheek-teeth associated with the type specimen (figs. 

 168<7, 168&) of II. mohavense are Hipparion-like in form and cementa- 

 tion of the crowns, in the form of the metaconid-metastylid column, 

 in the plications of the enamel, and in the occasional presence of the 



