58 



University of California Publications in Geology [Vol.9 



The occurrence of this species in the upper portion of the Etchegoin 

 formation shows the existence of a relatively advanced type of horse 

 in the California region, at a time near middle Pliocene. 



As nearly as can be determined from the fragmentary material 

 available this species is intermediate between advanced Pliohippus- 

 like forms and Equus. The internal wall of the protocone is convex, 

 instead of concave, as normally the case in Equus, but the anterior 

 end of the protocone is scarcely extended anteriorly beyond the isthmus 

 uniting protocone with protoconule. If the characters of this form 

 are satisfactorily represented in the specimens at hand, and* only one 

 form is represented, the species would seem to furnish a transition 

 between Equus and Pliohippus, 



Xo name is given to this form at present as more and better 

 material is desired before final estimation of the characters is made. 



Transmitted October £3, 1915. 



