436 University of California Publications in Geology [Vol. 7 



Upper Miocene. The representatives of the horse group known 

 from the Barstow Syncline include at least three forms : a Meryc- 

 Mppus of advanced type, near M. calamarius ; a large form near 

 Hypohippus; and a recently described species near Parahippus. 2 

 The association of Equidae, now known from the typical Mohave 

 Beds north of Barstow, seems to bear out the original suggestion 

 that these strata are near Upper Miocene in age. 



The fauna from the beds at El Pa.so Range contains some 

 elements which are quite distinct from those of the Barstow 

 region. Remains of horses are only fairly represented, but such 

 forms as are present seem to represent a different fauna from 

 that found in the Mohave Beds of the Barstow Syncline. 



At least two types of horses are known from the. beds in the 

 El Paso Range. One group closely aproaches the characters of 

 the Old World Hipparion, and may include two species. The 

 other type approximates Protohippus, and possibly includes two 

 species. It is doubtful whether typical Merychippus is repre- 

 sented, and remains of Hypohippus and Paraliippus have not 

 been certainly recognized. 



The general aspect of the representatives of the Equidae 

 found in El Paso Range is that of a fauna distinctly later 

 than that of the Barstow Syncline, and approximating very late 

 Miocene or early Pliocene. 



TTJPPARION( ?) MOIIAVENSE, n. sp. 



Type specimen no. 1H7S7, an upper premolar three with two associated 

 upper cheek-teeth, and several lower teeth presumably from the same 

 individual. From the Ricardo Beds, in the El Paso Range, north of 

 Mohave, California. 



Crowns of upper molars nearly straight; protocone small, separate from 

 protoconule and nearly circular in cross-section; enamel of the fossettes 

 very strongly crinkled; mesostyle of nearly uniform width. 



The crowns of the upper molars are nearly straight, or but 

 slightly curved, and not greatly elongated. In the type material 

 (figs, la to 36), in which the enamel plications are very strong, 

 the length of the crown measures about one and onedialf times the 

 transverse diameter. In other specimens, evidently but little worn, 



2 Merriam, J. C, Univ. Calif. Publ. Bull. Dept. Geo!., vol. 7, p. 427, 1913. 



