MIOHIPPUS. 53 



M. cuhphus p 4 is broader than m 1 , a progressive stage towards the equine condition; (4) it accents the M. eulophus char- 

 acter of the heavy but continuous meta- and protolophs which are not distinctly interrupted by conules. In the ectoloph 

 the parastyle, mesostyle, and ribs are sharply defined but not prominent, in fact, the ectoloph is somewhat flattened. (5) 

 Another feature is that the protoloph is more elongate transversely than the metaloph, causing these crests to be somewhat 

 asymmetrical as in M. latidens." 



Additional characters — (Osborn, 1918) (6) P 2-4 of less length than m 1 " 3 , i. c. PmsXMs. (7) Facial (preorbital) 

 region exceeds cranial (orbito-postorbital) region in length. 



While more progressive than M. intermedins in its high specific characters (1-5) M. meteulophus is sharply distinguished 



Fig. 30. Type of Miohippus meteulophus Osborn, Amer. Mus. 1210. (D) Original figure of type. One-half natural 

 size. After Osborn, 1904, PI. v, D. (1) Superior molars of type, partly reversed in drawing. Natural size. 



as follows: (8) the hypostyle rises directly on the posterior cingulum; it is not in the least separate; (9) it differs from 

 M. gidleyi in the conformation of the crests, the small size of p 2 , and the relatively large size of m 3 ; (10) as in Hypohippus 

 the external cingulum tends to cross the base of the parastyle; (11) the crests are relatively simple and continuous; (12) 

 postfossette partly indicated in the premolars; (13) lachrymal fossa vertically narrow, long and deep, extending down 

 into malar region; (14) parastyle flattened or angulate. 



Matthew (1915) regards these resemblances as pointing not especially toward Hypohippus but equally toward 

 Archceohippus or certain species of Parahippus. 



Miohippus brachystylus Osborn, 1904. 



Plates 1.8, 3.2. Text Fig. 31. 



Mesohippus brachystylus sp. nov., Osborn, Henry F. "New Oligocene Horses," Bull. Amer. Mus. Nat. Hist. Vol. XX, Art. XIII, 

 May 28, 1904, pp. 175-176, fig. 6, PI. v, E. 



Horizon and locality. — Big Badlands of South Dakota, near Cheyenne River, Leptauchenia zone. Type collected 

 by H. F. Wells, 1903. 



Type. — Amer. Mus. 11860, posterior portion of facial and cranial region of skull with complete upper dental series of 

 left side, adult. Measurements: p'-m 3 .082; m 1 " 3 .038; m 1 a.p. .0135, tr. .0175; m 3 tr. ,0155. 

 Type figure. — Text Fig. 31 of this Memoir. 



