1 10 



OSBORN: OLIGOCENE, MIOCENE, PLIOCENE EQTJIDiE. 



in fact, a composite of two jaw fragments, the symphysis and the (right) ramus belonging certainly to different indi- 

 viduals and probably to distinct species. The symphysis is evidently the primary type. The "right maxillary bone" 

 has not been located. Measurements: p 2 a.p. .022, tr. .019; m 1 a.p. .018, tr. .022. 



Type figure. — Text Fig. 84 of this Memoir. . 



/Vo. 9266 i-ectotype 

 AM 



2 



Fig. 84. Mcrychippus labrosus Cope, lectotype, Amer. Mus. Cope Coll. 8260. Mandibular symphysis and incisors 

 One-half natural size. 



Merychippus sejunctus Cope 1874.' 



Plates 11.1, 16.1,2,3, 19.1,2, 20,43.3, 48.1, 50.1,5, 53.3. Text Figs. 85, 85a, 86. 



Protohippus sejunctus, sp. nov., Cope, E. D. "Report on the stratigraphy and Pliocene Vertebrate Paleontology of Northern 

 Colorado," Bull. U. S. Geol. and Geog. Surv. Terr., Vol. I, No. 1, Jan. 21 (1873), 1874, p. 15, no figure. Same description included in 

 "Report on the Vertebrate Paleontology of Colorado," Ann. Rept. U . S. Geol. and Geog. Surv. Terr. (1873) 1874, p. 524, no figure. 

 "On the Origin of the Foot Structures of the Ungulates." The Amer. Naturalist, Vol. XV, No. 4, April, 1881, p. 271, fig. 3. 1 



Horizon and locality. — Pawnee Buttes, Pawnee Creek formation, northeastern Colorado, Middle Miocene, Mery- 

 chippus zone. Type collected by Edward D. Cope. 



Type and paratopes. — Amer. Mus. Cope Coll. 8291. (Cope) "Represented in my collections by a nearly complete 

 skeleton, with cranium and entire dentition, both mandibular rami and symphysis of a second; mandibles and dentition 

 of two others, with appropriate molar teeth." Type. "Complete skull and lower jaws with entire dentition and parts 

 of the skeleton associated, including the hind feet. Measurements: (Cope) " Length of entire molar series .124." (Gidley, 

 1907, p. 892) Total length of skull taken on basal line .325; p 4 a.p. .019, tr. .022; m 1 a.p. .0165, tr. .021. Cotype and 

 referred specimens Amer. Mus. 8254, 8273, 827S, 9378, 9383, 9389, 93S6, 9414; all from Pawnee Buttes. 



Type figure. — Cope 1881, fig. 3, not reproduced here. 1 



Characters. — (Matthew, 1913) (1) Size medium, p'-m 3 .123 (see Gidley); (2) protocone rather large, flattened oval, 

 united half way down; (3) fossette borders simple, fossette areas contracted; (4) pli caballin rudimentary or absent; (5) 

 metastylid not separate in P2; (6) metastylid and metaconid pillars forming a rather narrow, double column; (7) heel of 

 rr>3 broad, with internal fold. (8) Lachrymo-malar fossa? broad, sessile, sub-united; (9) preorbital region rather short. 

 (10) Ulnar shaft slender, united with radius except near proximal extremity; (11) metapodials and limb bones of moderate 

 length and slenderness; (12) unguals rather narrow. 



1 See also Cope, "The Perissodattyla," The Amer. Naturalist, Vol. XXI, No. 12, Dec. 1887, p. 1071, fig. 39, and "Hitherto Un- 

 published Plates of Tertiary Mammalia and Permian Vertebrata." Amer. Mus. Nat. History Monograph Ser. No. 2, 1915, Pis. cl., 

 cli. Plates prepared under the direction of E. D. Cope for the U. S. G. S. Survey of the Territories, with descriptions of plates by 

 W. D. Matthew. These plates represent the "Hayden Report, IV," of Cope's descriptions. 



