Sf BORDER C 



PERISSODACTYLA 



155 



very stout, with a well-developed keel on the distal articular surface ; lateral 

 metapodials slender, with short digits not reaching the ground. 



The genus Hipparion is distinguished from ther horse by its more delicate 

 structure, smaller size (being intermediate between the ass and the zebra in 



Pig. 211. 



Upper molar of A, Equus stenonis Cocchi. B, Hipparion gracile Kaup sp. C, Neohipparion dolichops 

 Matthew. D, Protohippus sp. 



this respect), by the anomalous character of its upper cheek teeth, and 

 especially by its tridactyl feet. In Europe it characterises the Lower and 

 Middle Pliocene deposits; it probably lived in great herds, and left behind 

 numerous remains at Eppelsheim, Hesse - Darmstadt ; at Mont Leb6ron, 

 Vaucluse ; Concud, Spain ; Baltavar, Hungary ; Pikermi, near Athens ; Samos, 



and elsewhere. H. gracile 



Kaup, H. mediterraneum, 



H. brachypus Hensel. 



J?»^ Middle Pliocene ; Per- 



pignan. H. crassum Ger- 

 vais. In China, H. 

 richthofeni Koken ; in the 



Fig. 212. 



Hipparion gracile Kaup sp. Lower Pliocene of Europe. 

 Restoration of skeleton. 



Fig. 213. 



Hipparion gracile Kaup sp. 

 Lower Pliocene, Pikermi, 

 near Athens. Upper molar, 

 showing separate inner 

 column (6). Vi. 



Siwalik, H. theobaldi Lydekker, and U. antilopinum Falconer. Hipparion is 

 also known from Algiers, Egypt and Persia. In southern Russia and in 

 Samos the small Hipparion minus Pavlow, together with H. gracile. 



Neohipparion Gidley (Fig. 211, C). Dentition like that of Hipparion, but 

 in some species the protocone of the superior cheek teeth, instead of being 

 cylindrical, is elliptical, and often even concave externally. In the typical 

 species N. whitneyi, the folding of the enamel is less marked, the ectoloph of 

 the external cusps is distinctly concave, the external pillar of the inferior 



