UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGICAL SCIENCES 



Vol. 13, No. 3, pp. 19-21, 1 text figure December 22, 192 1 



NOTE ON AN HIPPARION TOOTH FROM THE 

 SIESTAN DEPOSITS OF THE BERKELEY 

 HILLS, CALIFORNIA 



BY 



CHESTER STOCK 



Few remains of mammals are known from the Orindan and Siestan 

 Pliocene deposits of the Berkeley Hills although diligent search for 

 such material has been carried on from time to time during the past 

 quarter of a century. The Orindan and the Siestan in the region of 

 Mount Diablo have yielded likewise but scattered collections. 1 Among 

 the more important specimens from the Orindan near Mount Diablo 

 are several fragmentary teeth of horses of the Hipparion group. Re- 

 cently, Professor G. D. Louderback secured a tooth of an Hipparion 

 in a fresh-water limestone lentil of the Siestan on the east side of Bald 

 Peak, in the Berkeley Hills. In the section the limestone forms part 

 of a sedimentary series that includes also clay beds from which have 

 been described remains of the beaver, Dipoides lecontei. 2 



The upper tooth, no. 24241, figure 1, discovered by Professor 

 Louderback belongs to the premolar series. The Siestan specimen is 

 slightly curved and possesses a fairly heavy coating of cement. In 

 no. 24241 the parastyle and mesostyle are prominent. The borders 

 of the fossettes show considerable crinkling. The enamel folds of the 

 prefossette are particularly deep and numerous. The protocone nar- 

 rows anteriorly and posteriorly, no. 24241 differing in this character 

 from Hipparion platystyle and resembling certain teeth of Hipparion 

 from the Ricardo Pliocene deposits of the Mohave Desert, California. 



1 Merriam, J. C, Vertebrate fauna of the Orindan and Siestan Beds in Middle 

 California. Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 373-385, 19] 3. 



2 Merriam, J. O, Sigmogomphius lecontei, a new castoroid rodent from the 

 Pliocene near Berkeley. Univ. Calif. Publ. Bull. Dept. Geol., vol. 1. pp. 363-370, 

 1896. 



