192 



OSBORN: OLIGOCENE, MIOCENE, PLIOCENE EQUIDjE. 



Hipparion plicatile Leidy 1887. 



Fig. 155. Original fig- 

 ure of the type of Hippa- 

 rion plicatile Leidy, U. S. 

 Nat. Mus. 3292, an upper 

 molar of the right side. 

 One and one-half natural 

 size. After Leidy, 1887, 

 p. 310. 



Fig. 155a. Three views 

 of the type of \Hipparion 

 plicatile Leidy, U. S. Nat. 

 Mus. 3292, drawn under 

 the direction of Osborn by 

 B. Yoshihara. Natural 

 size. 



Text Figs. 155, 155a. 



Hippotherium plicatile. Leidy, Joseph. "Fossil Bones from Florida," Proc. Acad. Nat. Sci. 

 Phila. Vol. XXXIX, 1887 (sig. dated Dee. 13, 1887), pp. 309-310, text fig. p. 310. 



Horizon and locality. — (Leidy.) "... from Mixson's bone-bed, 10 miles east of 

 Archer, Levy County, Florida." Alachua clays or "Archer beds," Upper Miocene or 

 Lower Pliocene. Type collected by L. C. Johnson. 



Type. — U. S. Nat. Mus. 3292. (Leidy, Gidley.) An upper molar of the right side. 

 Measurements: (Leidy) diameters of upper molar a. p. .020, tr. .023, height of crown 

 (much worn) .030. 



Type figure. — Text Fig. 155 of this Memoir. 



Characters. — (Leidy, 1887) (1) Size approximating that of Equus asinus, exceeding 

 that of 77. ingenuwn. (2) Triturating surface of metaloph exhibiting a complexly folded 

 condition of the enamel quite different from that of //. ingenuum. (Gidley, 1907) (3) 

 Type apparently a true molar with the crown at least half worn away by use, hence 

 the elaborate plications [of the metaloph and crochet region] are a distinctive feature; 

 (4) double plicrochet and triple pli caballin folds; (5) single anterior and posterior folds 

 into pre- and postfossettes respectively; (6) protocone oval like that of II. venustum, and 

 //. ingenuum. (7) Clearly distinguished from IT. ingenuum by its much greater size and 

 by the difference in the character of the enamel foldings. 



Gidley observes that //. venustum, IT ingenuum and II. plicatile, all from the Atlantic 

 coast and from deposits apparently of Pliocene age, differ in some important respects from 

 the western American species, representing in general a slightly more recent phase of 

 development, especially in the greater length of the tooth crowns, stronger development of 

 the external stiles, and the much more elaborate plications of the enamel borders of the 

 fossettes. On the other hand, the retention of the primitive suboval form of the proto- 

 cone, nearly circular in cross section, as in some species of Mcrychippus, relates these 

 Atlantic coast species closely to the Hipparion gracile type of Europe. In foot structure, 

 from the fragments available, it would appear that it may more nearly resemble the 

 American Miocene forms. It seems not improbable that these animals belong to an 

 American branch of the Hipparion group of the Old World. 



Hipparion minor Sellards 1916. 

 Text Fig. 156. 



Hipparion minor, sp. nov., Sellards, E. H. " Fossil Vertebrates from Florida: A New Miocene 

 Fauna; New Pliocene Species; The Pleistocene Fauna," Eighth Ann. Rept. Florida State Geol. Surv. 

 1916, pp. 96-98, PI. 11, fig. 10, PI. 13, fig. 8. 



Horizon and locality. — (Sellards, p. 96) " A new hipparion from Florida is of inter- 

 est because of its miniature size. The species is represented by teeth obtained both from 

 the hard rock and from the land pebble phosphate deposits." This "Bone Valley forma- 

 tion of Brewster, Fla." is believed to be contemporaneous with the Alachua Clays 

 (Sellards, letter Sept. 24, 1917). Name of collector not given. 



Type. — (Sellards, pp. 96-97.) " As type of this species the writer selects specimen 

 No. 5867 of the Florida Geological Survey collection from the pit of the Amalgamated 

 Phosphate Company at Brewster. In addition two smaller teeth, from the hard rock 



