532 



University of California Publications in Geology [Vol. 11 



of the collection of equid remains known from the Snake Creek. One 

 of the common species of Merychippus is closely related to M. cala- 

 marius of the Santa Fe Upper Miocene. 



The oreodonts of Snake Creek and Ricardo are not easily com- 

 parable, but may be near the same stage of evolution. The camels are 

 also not widely different so far as can be determined. Drpmomeryx 

 present at Snake Creek is not more advanced than a Barstow form, 

 as is also the Merycodus of Snake Creek. Blastomeryx is present 

 at Snake Creek and unknown in both the Ricardo and Barstow. 

 The bovid form, Neotragocerus at Snake Creek is not known at 

 Ricardo, and approaches more nearly the stage of the Thousand Creek 

 antelopes. 



If it should appear that the Snake Creek represents more than 

 a single faunal stage, one assemblage may be near the stage of the 

 Ricardo or younger and one older. 37 " 



The Republican River fauna of northwestern Kansas represents 

 a stage recognized as near the beginning of the Pliocene. Matthew 

 and Cook, who have made a most careful comparison of this assem- 

 blage with the Snake Creek, consider that modernization is more 

 apparent in the latter. 37 '' The Republican River canid fauna contains 

 only advanced forms of the Aelurodon or Dinocyon type. The felid 

 forms are presumed to be machaerodont. The Equidae include 

 Ilypohippus, ProtoMppus, and Neohipparion. Two oreodonts, Mery- 

 cochoerus and Merychyus, are present, with camels of the genera 

 Procamelus and Pliauchenia. Dromomeryx and Blastomeryx are not 

 represented. Considering that the two areas discussed are widely 

 separated geographically, it would seem to the writer that the Repub- 

 lican River may not be far from the stage of faunal evolution shown 

 by the Ricardo. 



Relationship of the Ricardo to the Alachua of Florida is suggested 

 especially by similarity of the Hipparion species. The American 

 species most resembling the Ricardo hipparions include H. plieatile 

 and H. ingenuum of the Archer beds, and H. venustum from Ashley 

 River, South Carolina. This resemblance may be purely incidental, 

 but possibly indicates a close genetic relationship, and approximately 

 the same stage of early Pliocene for the beds in which these forms are 

 found. 



37i See Matthew, W. D., recently published review of Snake Creek fauna 

 appearing while present article is in proof. Bull. Amer. Mus. Nat. Hist., vol. 38, 

 pp. 183-185, 1918. 



■"ft Matthew, W. D., and Cook, H. J., Bull. Amer. Mus. Nat. Hist., vol. 26, 

 p. 368, 1909. 



