186 University of California Publications in Geology [Vol.9 



collections from the Great Basin region. The total characters, so far 

 as known, indicate that the species is much nearer to Hypohippus than 

 to any other group, and excepting- the separation of metaloph and 

 ectoloph it is not clearly distinguished from that genus. The gap 

 between this form and typical Hypohippus seems less than the spaces 

 between other anchitheriine genera. The new subgenus, Drymohippus, 

 proposed to include this form, bears the characters of Hypohippus 

 excepting in the separation of metaloph and ectoloph in the milk 

 dentition. Later investigations may add other distinctive characters. 



HYPOHIPPUS, near OSBORNI Gidley 



A lower molar (no. 19763, fig. 20) from locality 2027 represents 

 a species of Hypohippus near the form found in the Middle Miocene 

 of Virgin Valley in northern Nevada. This species is apparently 

 nearer to Hypohippus osborui than to H. equinus or to affinis. 

 Specimen no. 19763 is almost identical in dimensions with the Virgin 

 Valley form. The tooth resembles the Virgin Valley species in form 

 excepting in the character of the entostylid, which is relatively very 

 weak in no. 19763. It is not improbable that additional material may 

 show that the Nevada species is distinct from those previously des- 

 cribed from other regions. 



Comparative Measurements 



No. 12587 Hypo- 

 Virgin hippus 

 No. 19763 Valley osborni H. equinus H.affinis 



M„ anteroposterior diameter 22. mm. 23.8 23. 28.5 



M„ transverse diameter 16. 18.1 14. 20. 



M = , anteroposterior diameter .. 20.7? 21. 23.5 22. 



M 2 , transverse diameter 14.3? 14.4 16.2 12. 



Two fragments of upper molars evidently represent Hypohippus. 



MERYCHIPPUS, sp. 



The proximal phalanges of the protohippine horse (figs. 26 and 27) 

 from locality 2027 represent a type almost exactly similar to proximal 

 phalanges of Merychippus from the Middle Miocene of Virgin Valley. 

 They are also very close in form to phalanges of Merychippus from 

 the Barstow Miocene. The Cedar Mountain specimens show a little 

 less median constriction than the average specimens from the Barstow 

 fauna, and in this respect are more like the Virgin Valley form. 



