154 THE MERYCOIDODONTID/E 



respects it resembles the comparable bone in the type species. The distal end of the fibula of 

 M . ccenopus expands anteroposterior^, is laterally compressed, and is partly covered by the tibia. 



The structure of the manus is similar to that in Promerycochosrus montanus. It is a trifle 

 longer than that of M. matthewi and a little more compact. The metacarpals are very close to those 

 of M. magnus, but the phalanges are longer and to a certain degree slenderer. 



In the pes Mt. II has a very small proximal articular surface for the mesocuneiform, which is 

 transversely placed, as in Merycoidodon, and is not oblique, as it is in Sus. The proximal end of 

 Mt. II is lower than that of Mt. Ill, thus excluding the former from contact with the ectocunei- 

 form. In the earlier forms of this family Mt. II is higher than Mt. Ill and touches the ectocunei- 

 form. Mt. Ill is short and stocky, and its proximal end lies in the same transverse plane with 

 Mt. IV. This is like the structure in Sus, while in Merycoidodon Mt. Ill is higher and touches 

 the side of the cuboid. On the tibial side is a tiny facet for the mesocuneiform, an unusual character 

 which seems to be a beginning of the adaptive manner of reduction. Mt. IV is stronger and heavier 

 than that of Merycoidodon, and the posterior hook is stronger and less pointed. Mt. V articulated 

 with the cuboid by a small, concave, and obliquely placed head. 



Professor Scott considered that a continuation of the evolutionary trend, such as is evidenced in 

 the structure of this manus and pes, would have led to the same condition as that now found in 

 Dicotyles. 



The metatarsals in Scott's species are of approximately the same width, though somewhat 

 longer than those of M. proprius, and the total width of the pes of the latter species is slightly wider 

 than that of the former. 



In general these bones compare most favorably with those of M . proprius, but in the absence 

 of associated skull or tooth remains we cannot definitely assign Scott's species to any other of the 

 better known forms of Mery cochcerus. 



Merycochoerus magnus Loomis 1924 

 Figs. 4, 113; PL XXI 



Original Reference: Miocene oreodonts in the American Museum. Bull. Amer. Mus. Nat. Hist., LI, 

 Art. 1, pp. 28-30, figs. 5, 16-17. 



Type Locality: Seven miles northeast of Agate, Nebraska. 



Geologic Horizon: Lower Miocene (upper Harrison). 



Types: Holotype, Cat. No. 14242 A.M.N.H., skull, jaws, and fore and hind limbs of an old individual. 

 Paratype, Cat. No. 14238 A.M.N.H., upper and lower dentition of a younger individual. 



Specific Characters: The skull is about a sixth longer and a seventh wider than that of 

 M. proprius. The maximum expansion of the zygomata is at the glenoid surfaces. The malar part 

 is exceptionally deep beneath the orbits, and the squamosal part gradually decreases in width, 

 although it is moderately strong throughout. The posterior part rises somewhat abruptly, with the 

 uppermost portion curving slightly forward. The nasals are rather short and are uniform in width. 

 They are obtuse posteriorly and slightly convex transversely. The antorbital fossa is well marked. 

 The maxillaries form a sigmoid curve along the upper contour in advance of the anterior narial 

 opening. These bones are depressed just in front of the opening to a much greater extent than in 

 any other species of this genus. The frontals are wide and somewhat arched above the orbits, and 

 apparently they do not extend in advance of the lacrimal bone. The orbits are elevated and are 

 moderately small, with the greater diameter anteroposteriorly. They look mainly sidewise but also 

 slightly forward and upward. The temporal ridges join in a plane above the posterior of the glenoid 

 articular surfaces, so that the sagittal crest is very short and rather low. The supraoccipital crest is 

 small and low, and the wings wide apart. The crest probably does not overhang beyond the occipital 

 condyles. The brain case is greatly shortened and broadened. In fact, the whole cranial area is 

 much foreshortened. The external auditory meatus is small and round and is directed upward and 

 outward from the moderately small oval-shaped bulls. It lies considerably below the tip of the 



