PLATE CXLVIIla. 
Miocenr Equip#. TrmnTH AND Brain Cast OF MERYCHIPPUS, ETC. 
Fic. 
Fic. 
HirGeame 
Fia. 
Fias. 5-7. 
Fig. 8, 8a. 
Fias. 9-11. 
Nomenclature 
Cope 1880-3 Revised 1915 
Hippotherium sphenodus Merychippus sphenodus 
Protohippus (in part) Protohippus sp., aff. perditus 
Protohippus perditus (in part) Merychippus sejunctus 
Protohippus insignis (Cope, non Leidy) Merychippus labrosus ete. 
Protohippus sejunctus (in part) Merychippus isonesus 
Hippidium spectans Pliohippus spectans 
Merychippus ? sphenodus (Cope, 1889). Upper premolars; paratype, natural size, 
Amer. Mus. No. 828la, Cope Coll., Pawnee Creek beds, Colorado. 
? Merychippus, unidentified specimen, upper molars. 
Merychippus sejunctus. Upper teeth, natural size, crown view. Amer. Mus. No. 
8254, Cope Coll., recorded as ‘‘East of Laramie Peak, Wyoming.” 
Protohippus sp., aff. perditus. Upper teeth, crown view, natural size. Am. Mus. No. 
8340, Cope Coll., Republican River Bed, Nebraska. Hind foot of this individual 
figured on pl. CXLIX. 
Type specimens of Protohippus labrosus Cope, Amer. Mus. No. 8266, Pawnee Creek 
Bed, Pawnee Buttes, Colorado. Fig. 5, upper teeth, crown view, natural size; 
fig. 6, 6a, lower jaw external and superior views, half natural size; fig. 7, upper 
jaw, half natural size, external view. Part of this specimen is now missing, only 
the lower jaw (fig. 6) being identifiable. This lower jaw is a composite of two 
individuals, the symphysis belonging certainly to a different individual and 
probably to a distinct species from the remainder of the jaw, which along with the 
upper teeth figured here (fig. 5) but now lost, agrees very nearly with Merychippus 
sejunctus. The symphysis, however, which in conformity with the author’s 
description and evident intent must be regarded as the primary basis of the 
species and selected as lectotype, is clearly distinct from M. sejunctus and cannot 
be correlated with any of the better known species. W.D.M., 1913. 
Merychippus isonesus, natural braincast, lateral and superior views. From the 
specimen figured on pl. CXLIX. Amer. Mus. No. 8105, Cope Coll., Deep River 
beds, Deep River (Smith Creek), Montana. 
Pliohippus spectans (Cope, 1880). Upper teeth, natural size, type specimen, 
Amer. Mus. No. 8183, Cope Coll., Maseall formation, Cottonwood Creek, John 
Day Basin, Oregon. Fig. 9, 9a, first or second, upper molar, crown and anterior 
views; fig. 10, second upper premolar crown view; fig. 11, upper incisor, crown 
view. 
