G4 



osborn: OLIGOCENE, MIOCENE, PLIOCENE EQUID.E. 



11275 from John Day River, Ore., collected by O. C. Marsh, November 1st, 1871, and consists of eleven upper molar and 

 premolar teeth. The matrix cannot be discerned as the teeth are individual teeth. The second specimen is Yale Mus. 

 11282, consisting of portions of both hind limbs which correspond with Marsh's type measurements; the only locality 

 given is Oregon; the matrix was originally green but has partly weathered into gray. The third specimen [cotype], 

 Yale Mus. 12230 consists of a skull, since partly restored by Lull; collected by Marsh November 1st, 1871; matrix seems 

 to be gray ; the reference of this last specimen to M. annectens is decidedly questionable. The gray matrix is associated 

 with the Upper John Day beds." Measurements: (Marsh, 1S74) p 1 " 4 .061; m 1 " 3 .046; m 3 a.p. .014, tr. .0195. 



Type figure— Plate 3.15, text Fig. 43 of this Memoir. 



This species is the genotype of Miohippus. 



Characters — (Marsh, 1874, pp. 249-250) Based upon type and cotype specimens (Yale Mus. 11275, 11282, 12230). 

 (1) Anterior margin of orbit above front of third superior molar. (2) Enamel of all teeth preserved, smooth; (3) prominent 

 tubercle in medivallum but no internal cingulum. (4) Distinguished from Miohippus (A.) condoni as follows: (5) in 

 M. (A.) condoni the enamel is rugose; (6) small cusp [hypostyle] behind the posterior crest is parallel with the posterior 

 basal ridge [cingulum] and (7) the inner tubercle between the transverse crests is entirely wanting. (8) The size of the 

 animal exceeds that of a sheep, with longer limbs. 



Fig. 43. Miohippus annectens Marsh, Yale Mus. 11275. (Right upper) Crown view of p 2-3 of the type, of the right 

 side. (Left upper) same view of p 4 , m 3 of the left side. Drawing by S. Oka. (Lower) Composition drawing, under the 

 direction of Osborn, of the type superior grinding teeth of the right and left sides, p 2-3 , p 4 , m 3 , partly reversed in draw- 

 ing. All figures natural size. 



(Osborn, 1918) The characters of M. annectens must now be based solely upon the excellent type specimen Yale 

 Mus. 11275 figured herewith. The association by Marsh of the other specimens as cotypes cannot be confirmed from the 

 evidence presented by Lull (1915). 



Miohippus acutidens Sinclair, 1905. 

 Plate 4.7. Text Fig. 44. 



Mesohippus acutidens, n. sp., Sinclair, Wm. J. "New or Imperfectly Known Rodents and Ungulates from the John Day Series," 

 Univ. of Calif. Publ. Bull. Dept. Geol, Vol. 4, No. 6, July, 1905, p. 1-41, PI. xviii. 



Horizon and Locality. — (Sinclair) " Promerycochcerus beds (?), Upper John Day. Powell's Ranch on the Middle 

 Fork of the John Day River about five miles above Ritter, Grant Co., Oregon." Name of collector not given. 



Type. — Univ. Cal. Pal. Coll. 376. (Sinclair) "Cranium, portion of the left fore limb, and a few vertebral fragments; 

 No. 376, Univ. of Cal. Pal. Coll." Measurements: premaxillee to condyles 238; p^m 3 .085; m 1 " 3 .0385; height of canine 

 .0175; m 1 a.p. .013, tr. .016; in 2 a.p. .013, tr. .0103; m 3 a.p. .0125, tr. .016. 



Ty pc figure. — Text Fig. 44 of this Memoir. 



Characters. — (Sinclair, 1905, p. 141) "Superior canines long and pointed, with acute anterior and posterior edges. 



