19 



Without this material, I should have hesitated to separate the two 

 species above described as uew 5 as it is, I have no questiou that they 

 are well defined, and are not the species described by Dr. Leidy, under 

 the name of MerycMppus. The two lower jaws at my disposal agree in 

 dimensions with each other, and with the superior molars, and with Dr. 

 Leidy's types with which I have compared them, four of them having 

 the same extent as five of those of the two species above described. In 

 two successional superior molars little worn, one of the inner columns 

 (the anterior) is not yet united with its corresponding crescent, and the 

 borders of the lakes are more plicate than in more worn examples. 



Protohippus placidus Leidy — 



A portion of the skeleton of this species was excavated by myself 

 from the rock of the Pliocene formation, which was accompanied by 

 two teeth characteristically those of this species, and the only ones I 

 obtained which are referable to it. They are readily known from their 

 small size absolutely, and it would seem relatively also. The vertebrae 

 are similar in size and proportions, ;but the metatarsus is materially 

 shorter than that of P. sejunctus, and the phalanges of all the toes, and es- 

 pecially the cofiin-bones, considerably^ stouter. Compare measurements 

 with those given above. 



Measurements. M 



Length median metapodial bone 17 



Expanse of condyles of lateral metapodials. 042 



Length of fist lateral phalange 024 



Antroposterior width of first lateral phalange 016 



Length of coffin-bone medially 041 



Width between angles 037 



Width of articular face 02G 



Height of coffin-bone behind 022 



Thus both coffin-bones are larger, wider, and fiatter than those of P. 

 sejiinctus, a character i^rovided for by the greater, lateral distal expansion 

 of the metapodial bones. The shortness of the metapodial bone is not 

 due to thefact of its being a metacarpal ; the femoral condyles are adherent 

 to it in the matrix, and there are proximal facets for the ento- and meso- 

 cuneiform bones. Were the bone a metacarpal, this facet would relate 

 to the trapezoides, a contact which does not exist in either of the genera 

 of the three-toed horses, Hippotherium and Anchitherium according to 

 Kowalesky*. 



ARTIODACTYLA. 



Merychyus major Leidy Anc. Faun. Dae, Nebr., 121. 



A single superior first molar presenting some peculiarities, perhaps 

 individual. 



Merychyus elegans Leidy, Loc. Cits., p. 118. 



A mandibular ramus with the molars and last premolar ; a little lar- 

 ger than Leidy's specimens from Nebraska. 



Procamelus, sp. 



Numerous parts of skeletons of a large species without teeth ; possibly 

 the P. niohrarensis Leidy. 



*Palaeontojriapbica 1873, Pl. VII. 



