UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 9, No. 18, pp. 525-534, 18 text-figures Issued March 20, 1916 



RELATIONSHIP OF EQUUS TO PLIOHIPPUS 

 SUGGESTED BY CHARACTERS OF A NEW 

 SPECIES FROM THE PLIOCENE 

 OF CALIFORNIA 



BY 



JOHN C. MEERIAM 



CONTENTS 



PAGE 



Introduction 525 



Pliohippus proversus, n. sp 526 



Relationships 530 



Measurements 534 



INTRODUCTION 



Recent studies of late Cenozoic Equidae 1 from the Pacific Coast 

 province of the United States have shown the existence of a California 

 Pliocene horse exhibiting advanced characters in some respects inter- 

 mediate between those of typical Equus and typical Pliohippus. As 

 considerable uncertainty has existed concerning the immediate an- 

 cestry of Equus, any evidence furnished by the new California form 

 is of special significance, and should therefore be presented in detail 

 for use in studies on the evolution of this group. It seems particularly 

 desirable to make available significant new materials received since 

 the last published reference to this peculiar form. 



The studies on West Coast Equidae leading to the statement in the 

 following article have been greatly facilitated by cordial co-operation 

 of Professor Henry F. Osborn and Doctor William D. Matthew of the 

 American Museum of Natural History. Through courtesies extended 

 in the use of collections and of organized studies made by the Museum, 



1 Merriam, J. C, Trans. Amer. Phil. Soc, n. s., vol. 22, part 3, p. 33, 1915; 

 also Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, p. 56, 1915. 



