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University of California Publications in Geology [Vol. ll 



the ectoloph. The protoconule is distinctly separate from the proto- 

 cone ; it is considerably elongated and flattened and its inner end 

 overlaps the protocone. The hypostyle is larger than in Hypohippus 

 and Archaeohippus, and there is a more distinct cuplike depression 

 behind it. There is no suggestion of a crochet, though several plate- 



Fig. 33. Parahippus? mourningi Merriam. P 3 to M», no. 19764, natural size. 

 Barstow Miocene, Mohave Desert, California. 



like projections arise from the anterior side of the outer end of the 

 metaloph. The cingulum is well developed on the posterior side, and 

 less distinctly on the anterior side between the protocone and proto- 

 conule. There is no shelf of the cingulum on the inner or lingual side 



34 35 



Fig. 34. Paraliippus? mourningi Merriam. Dm 3 , Dm 4 , and M 1 , no. 19840, 

 X 1%- Barstow Miocene, Mohave Desert, California. 



Fig. 35. Arclweoliippus ultimus (Cope). Upper molar, no. 1689, X 1%. 

 Mascall Middle Miocene, John Day Begion, Oregon. 



of the tooth. The cusps or ridges of the crown are somewhat higher 

 than in Archaedhippus or in Hypohippus. The surface shows a 

 degree of rugosity more pronounced than seems characteristic of 

 Hypohippus or of Archaeohippus. No trace of cement is evident upon 

 the crown. 



