MIOHIPPUS. 



59 



Miohippus equiceps (Cope) 1878. 



Plates 3.10, 5.4,5, 6.1. Text Fig. 37. 



Anchitherium equiceps, sp. nov., Cope, E. D. "On Some of the Characters of the Miocene Fauna of Oregon," Proc. Amer. Philos. 

 Soc, Vol. XVIII, 1878-1880 (sig. dated Dec. 26, 1878), p. 73, no figure. Palwonlological Bull. No. 30, " Dec. 3, 1878." 



Horizon and Locality. — Miocene of Oregon, horizon probably Middle John Day, Diceratherium zone. 



Type. — Amer. Mus. 7261. Skull and jaws. (Cope) " This animal is represented by a portion of the skeleton including 

 the complete cranium of one individual with [cotypes] mandibular rami of several others." Measurements: (Cope) 

 total length of cranium .280; length of molar series .100; length of premolars .053; m 1 a.p. .0135, tr. .0165; m 3 a.p. .0135, 

 tr. .0170. 



Type figure. — Plates 3.10, 5.5, 6.1, text Fig. 37 of this Memoir. 



Fig. 37. (Upper) Type of Miohippus equiceps Cope, Amer. Mus. Cope Coll. 7261. One-half natural size. Drawing 

 by B. Yoshihara. (Lower) Superior molar-premolar series of type. Natural size. 



Characters. — (Cope, 1878, pp. 73, 74) (1) Preorbital region but little concave; (2) anterior border of orbit above 

 posterior half of first true molar. (3) Molars with a tubercle between the anterior lobes; (4) a weak cingulum around inner 

 base of protoloph; (5) p 2 with cingulum around protoloph and metaloph; (6) a large three-sided hypostyle; (7) external 

 basal cingulum robust; (8) para- and metacones with median ridges well marked. (9) It differs from the type of Miohippus 

 (A.) condoni in the presence of median internal tubercle and cingulum, and (10) also in the presence of a trihedral instead 

 of a linear hypostyle. 



