26 GEOLOGICAL SURVEY OP TEXAS. 



pei-ditus; but it differs from that species, as Leidy had already shown, in 

 the deep preorbital fossa. On the otlier hand, the molars referred to a 

 species under the name of P. swpremus are appropriate in size and char- 

 acters to the form whose deciduous molars form the t3'pe of Leidy' s origi- 

 nal description. 



Protohippus labrosus. Cope, Bulletin U. S. Geol. Survey of Terrs., 

 I, 1874, p. 13; Ann. Report U. S. G. Survey Terrs., 1873 (1874), 523. 



Represented in my collection by a right maxillarj^ bone which contains 

 the five anterior molars, with which was found a nearly complete mandi=' 

 ble containing nearly all the molars, with the canines and incisors. The 

 form of the preorbital region can not be distinctly made out. The species 

 differs from the P. sejunctus in the close contiguity of tlie canine and incisor 

 teeth, which do not present a short diastema, as in P. sejunctus. In its 

 measurements it is smaller than the P. perdituSs and the enamel borders 

 of the lakes are more simple than in either that species or the P. sejunctus 

 at the corresponding age. Northeast Colorado. 



Protohippus castilli. Cope. Proceeds. Amer. Philos. Society, 1885, 

 p. 151, fig. 2. 



Represented by a single superior molar tooth in my collection from the 

 Miocene clays of Tehuichila, Vera Cruz, presented to me by Dr. Santiago 

 Bernard. This tooth is about the size of that of the P. pe)'ditus, and 

 differs from corresponding ones of that species in the relatively greater 

 transverse extent of the crown, proportionately greater width of the lakes, 

 and smaller size of the internal columns. The opposed lake borders 

 are folded as in the corresponding stage of P. perditus, but the loop of 

 the anterior lake is not so well defined. 



Protohippus placidus, Leidy, Extinct Mammalia Dakota-Nebraska, 

 1869, pp. 277-328, pi. XVIII, figs. 39-48; XXVII, figs. 6, 7; Cope, 

 Bulletin U. S. Survey Terrs., 1873 (1874), (exclusive of bones of skele- 

 ton). Hlpparlon gratum, Leidy, op. cit., 287pl. XVIII, figs. 25-30. 

 Hippotlierium gratum, Leidj'; Cope Proceeds. Amer. Philos. Society, 

 1889, figs. 16, 17. 



Represented in my collection bj^ molar teeth from Northeast Colorado 

 (E. D. Cope) and Dundy county, Neb. (F. Hazard). It is the most 

 abundant species in the Loup Fork bed of Donley countj^, Texas, as will 

 be described below, with the P. parvulus, the smallest species of the 

 genus. 



protohippus pachyops, Cope. 



Sp. nov. Plate XI, Figure 1; Plate XII; Plate XVII, Figures 2, 3. 



Represented by a cranium with lower jaw, from which have been 

 broken away all posterior to the orbits, and all anterior to the second pre- 

 molars. 



The malar-maxillary ridge is obtusely rounded, and there is no pre- 



