HIPPARION. 193 



phosphate deposit, Nos. 1167 and 1246, are referred to this species.". . .Measurements: Sellards, p. 97) "The antero- 

 posterior measurement of the type specimen is 13 — % mm.; the greatest transverse measurement is 13 mm. The 

 anteroposterior measurement of specimen 1167 [referred], which may be a milk tooth is 11 mm., while the transverse 

 measurement is 11 mm." 



Type figure. — Text Fig. 156 of this Memoir. 



Characters. — (Sellards, pp. 97-98) "The enamel bordering the lakes in this small species is very much compli- 

 cated. The inner column of the tooth is elipsoidal in the cross section. The species may be known as Hipparion minor 

 .... Of the hipparions, four species have now been described from Florida. Of these the largest is Hipparion princeps, 

 the type and only known specimen of which was found on Peace Creek and hence is of uncertain geologic age. The two 

 species, Hipparion plicatile and Hipparion. ingenuum, were described by Leidy from the Alachua clays, but are present 

 also in the hard rock phosphate deposits and in the bone valley formation. Of the four species, H. princeps is by far the 

 largest, while the one here described as H. minor is much the smallest. The presence of the three species of hipparions 

 in the Dunnellon and Bone Valley formations is one of the strong arguments for the essential contemporaneity of these 

 two formations." 



Fig. 156. Hipparion minor Sellards, Fla. State Geol. Surv. Coll., type, 5S67, and paratype, 1167. After Sellards, 

 1916: PI. 11, fig. 10, PI. 13, fig. 8, side and crown views of the type; PI. 13, fig. 7 crown view of the paratype. Natural size. 



Hipparion mohavense Merriam 1913. 

 Text Fig. 157. 



Hipparion (?) mohavense, n. sp., Merriam, J. C. "New Protohippine Horses from Tertiary Beds on the Western Border of the 

 Mohave Desert," Univ. Cal. Publ. Bull. Dept. Geol. Vol. 7, No. 23, Dec. 22, 1913, p. 436, figs. l'a-3b. 



Horizon and locality. — (Merriam, p. 436) "From the Ricardo Beds, in the El Paso Range, north of Mohave, Cali- 

 fornia." Lower Pliocene. Type collected by C. L. Baker. 



Type. — Univ. Cal. Pal. Coll. 197S7. (Merriam, 1913, p. 436.) " . . .an upper premolar three with two associated 

 upper cheek-teeth, and several lower teeth presumably from the same individual." Measurements: (Merriam) 





P 3 



M 1 



M 2 



Anteroposterior diameter 



022 



.0214 



.0216 







.022 



.020 





032 + 



.032 + 



.037 



Type figure. — Text Fig. 157 of this Memoir. 



Characters. — (Merriam, p. 436) (1) Crowns of upper molars nearly straight or but slightly curved, crowns not 

 very elongate, length about one and one-half times the transverse diameter, in less worn specimens crowns may equal 

 about twice the transverse diameter; (2) cement layer well developed on the outer and inner sides; (3) parastyle and 

 mesostyle prominent, mesostyle especially strong on premolars, broadening toward the base; (4) outer sides of paracone 

 and metacone may show a slight tendency to formation of a median rib, protocone, free almost to base, nearly circular 

 in cross section or slightly elongate anteroposteriorly; (5) anterior and posterior borders of pre- and postfossettes with 



