MERYCHirPUS. 



Merychippus paniensis Cope 1874. 



Plates 11.2, 16.4,5,6, 18.1,5, 25.5, 34.1,2, 43.2, 48.2, 50.2,6, 53.2. Text Fig. 83. 



Hippotherium paniense, sp. now, Cope, E. D. "Report on the Stratigraphy and Pliocene Vertebrate Paleontology of Northern 

 Colorado," Bull. U. S. Geol. and Geog. Sun'. Terr., Vol. I, No. 1, Jan. 21, (1873) 1874, p. 12, no figure. Same description included in 

 "Report on the Vertebrate Paleontology of Colorado," Ann. Re pi. U. S. Geol. and Geog. Surv. Terr., 1874, p. 522, no figure. "A Review 

 of the North American Species of Hippotherium," Proe. Amer. Phil. Sec., Vol. XXVI, 1889 (sig. dated June 5, 1889), pp. 447-448, figs. 

 13a-14. 



Horizon inn/ locality. — Pawnee Creek formation, Pawnee Buttes, northeastern Colorado, Merychippus zone, Middle 

 Miocene. Type collected by Edward D. Cope. 



Type. — Amer. Mus. Cope ('oil. 8249. A right upper molar, m 1 . Measurements: (Gidley, 1907, p. 890) m 1 a. p. 

 .0185, tr. .020, height of crown outside .Q26, inside .0115. Cotype. A left upper molar, m\ Amer. Mus. Cope Coll. 8250. 

 Measurements: (Gidley, op. cit.) m 3 a. p. .020, tr. .0185, height of crown outside .030, inside .Old. 



Type figure. — Text Fig. 83 of this Memoir. 



Characters. — (Cope, 1874, Osborn, 1918) (1) Enamel borders of hypostyle, of metaloph, and crochet region ptychoid; 

 (2) protocone separate in incompletely worn crown; (3) marked curvature of the crown; (4) crown of intermediate length, 

 hypsodont. Cope considered this animal an hipparion. Gidley (1907) considered the species not well characterized. 

 Matthew (1913) refers to it a number of characteristic specimens from the Pawnee Creek formation, namely, parts of 



Fig. 83. Original figures of the type of Merychippus paniensis Cope, Am. Mus. Cope Coll. 8249, a right upper molar, 

 m 1 . Natural size. After Cope, 1SS9, figs. 13a-14. 



skull and jaws, fore and hind limbs and feet, Amer. Mus. 9382; also Amer. Mus. 9039, 9093, 9413, 9460, and adds the 

 following characters (1913): (1) size median, same as M. sejunctus; (2) hypsodonty as in M. sejunctus; (3) protocone 

 separate to near base or united half way up crown; (4) protocone typically small, round-oval; (5) pli caballin fold well 

 developed; (6) lachrymal fossa deep, abrupt, commencing close to border of orbit; (7) limbs relatively shorter than in 

 M. sejunctus, lateral digits more robust; (8) ungual phalanges short and narrow. Matthew (1913) regards it as close to 

 M. isonesus of the Mascall but somewhat more progressive. 



Referred specimens are, Amer. Mus. 8255, 8290, 9382, 9403, 9413. 



Merychippus labrosus Cope 1874. 

 Text Fig. 84. 



Protohippus labrosus sp. nov., Cope, E. U. "Report on the stratigraphy and Pliocene Vertebrate Paleontology of Northern Colo- 

 rado," Bull. U. S. Geol. and Geog. Sure. Terr., Vol. I, No. 1, Jan. 21, (1873) 1874, p. 13, no figure. Same description included in 

 "Report on the Vertebrate Paleontology of Colorado," Ann. Rept. V. S. Geol. and Geog. Sure. Terr., 1874, p. 523, no figure. 



Horizon and locality. — Pawnee Buttes, Pawnee Creek formation, Merychippus zone, Middle Miocene of northeastern 

 Colorado. Type collected by Edward D. Cope. 



Type. — Amer. Mus. Cope Coll. 8200. A mandible. (Cope) "The specimen of P. labrosus embraces also the right 

 maxillary bone, containing five molars; a second specimen [paratype] includes three superior molars of the left side; it is 

 also represented by several isolated molars." The type, Amer. Mus. 8266, consists primarily of the "mandible," which is, 



