1919] Merriam: Tertiary Mammalian Faunas of Mohave Desert 507 



Measurements 



No. 21423 No. 21424 No. 21425 



M 1 , anteroposterior diameter 24.2 mm. o23.5 24 



M 1 , transverse diameter 23.8 al9 24 



M 1 , height of crown 39 42.6 37 



a, approximate. 



The large protohippine horses of the Barstow fauna represented in 

 Merychippus e. stylodontus, M. intermontanus, and the Protohippns 

 or PUohippus described above, are antecedent types such as we 

 might expect to find in the ancestors of the Ricardo and Etchegoin 

 Protohippus and PUohippus species. PUohippus 

 fairbanksi of the Ricardo fauna and P. coalingensis 

 of the Etchegoin may either or both be derivations 

 of Merychippus intermontanus of the Barstow. PUo- 

 hippus tantalus is as yet imperfectly known, but may 

 be a derivative of a form near one of the Barstow 

 types. 



SUIDAE 



A single astragalus of a suilline form, no. 22469 

 (fig. 83), from locality 1398 in the Barstow beds rep- 

 resents a dicotyline form, but a generic determina- 

 tion seems doubtful. This specimen shows the pres- 

 ence in this fauna of the peccary-like forms so well 

 represented elsewhere in the American Miocene. 



Fig. 83. Pros- 

 the n nop s ? , sp. 

 Astragalus, no. 

 22469, natural 

 size. Barstow 

 Miocene, Mohave 

 Desert, Califor- 

 nia. 



OREODONTIDAE 



MERYCOCHOERUS? BUWALDI, n. sp. 



Type specimen, no. 21350, an upper dentition from locality 2057, Barstow beds, 

 Barstow syneline, north of Barstow, California. 



Fragmentary oreodont remains representing a form near Mery- 

 cochoerus were found sparingly by Baker in the Barstow region in 

 1911. In 1913 Buwalda and Mourning found more abundant material 

 showing a complete upper cheek-tooth series, and a considerable part 

 of the lower dentition. 



This species is near Merycochoerus in general characters of the 

 dentition and skull. It is at least as advanced as that genus in 

 specialization of the premolars and in relative proportions of the 

 molar and premolar series. 



