426 University of California Publications in Geology [Vol.10 



At localities in the Orinda, and in beds presumed to be higher 

 than those of the horizons at San Pablo Bay, the following forms have 

 been obtained : 8 



Orinda Fauna, Contra Costa Hills 

 Hipparion platystyle Merriam 

 Hipparion, near mohavense Merriam 

 Prosthennops, sp. 

 Proeamelus, sp. 

 Pliauchenia, sp. 

 Tetrabelodon ?, sp. 

 Dipoides lecontei (Merriam) 



If any suggestion of sequence is given in the Pinole Tuff-Orinda 

 section, it appears to be that Hipparion occurs at a horizon somewhat 

 higher than that of the Pliohippus forms ; but the stratigraphic suc- 

 cession is so imperfectly known that such a conclusion seems not at 

 present to be fully warranted. 



The Tcjon Hills fauna found in the Chanac formation at the 

 southern end of San Joaquin Valley occurs in beds which rest upon 

 marine San Pablo Upper Miocene, and are presumably unconformable 

 upon that formation. The fauna includes the following forms: 



Chanac Fauna 

 Protohippus tehonensis Merriam 

 Pliohippus, sp. 



Hipparion gratum tehonense Merriam 

 Hipparion, near molle Merriam 

 Rhinoeerotid, indet. 

 Prosthennops, sp. 

 Camelid, indet. large 

 Meryeodus, near necatus Leidy 

 Proboscidean (Tetrabelodon?), sp. 



In this fauna the hipparions are the most abundant forms. They 

 represent two small species, one of which is very close to Hipparion 

 gratum of the Great Plains region. The Prosthennops suggests the 

 Pliocene species of the Great Valley of California. The Meryeodus 

 is near necatus Leidy, which appears both in the Barstow Upper 

 Miocene and in the Ricardo Lower Pliocene of the Mohave Desert a 

 few miles to* the east. 



Comparison of the Chanac fauna with the available Etchegoin and 

 Tulare faunas shows that the Tejon Hills stage may be comparable 



s Merriam, J. C, Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 373-385, 1913. 



9 Merriam, J. C, Mammalian remains from the Chanac formation of the 

 Tejon hills, California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 10, pp. 111-127, 

 1916. 



