418 University of California Publications in Geology [Vol. 7 



very desirable to have more material of E. niobrarensis for a 

 fully- satisfactory comparison. 



Comparison with Equus laurentms Hay. — A fine skull from 

 supposed Pleistocene near Lawrence. Kansas, recently described 

 by Hay, 17 and designated as the type of a new species, Equus 

 laurentius, represents a form quite different from the California 

 E. occidentalism The skull and teeth in E. laurentms are much 

 smaller; the nose is relatively longer and narrower; the width 

 behind the orbits is relatively greater ; the mandible is much 

 more slender, being narrower or lower below the premolars ; the 

 inferior border of the mandible is straight instead of sinuous 

 as in E. occidentalis ; the orbits seem to be relatively larger. 



SUMMARY 



The species of horse commonly represented in the Pleistocene 

 beds of Rancho La Brea is not separable from Equus occidentalis 

 first described by Leidy from Tuolumne County, California. 



As represented by the excellent series of specimens from 

 Rancho La Brea, Equus occidentalis is characterized by its large, 

 heavy head, short and broad nose, high and heavy mandible, 

 and relatively simple enamel pattern of the cheek-teeth. 



« Hay, O. P., Proe. U. S. Nat. Mus., vol. 44 (no. 1969), p. 584, 1913. 

 Transmitted September 18, 1913. 



