Igg the merycoidodontim: 



a rather unusual position for the manus. The facet for the scaphoid is markedly oblique, as in 

 Promerycochoerus. The facet was flexed very high on the radial posterior angle. The lunar facet is 

 more highly placed and is of relatively greater transverse diameter than in Merycoidodon. 



The ulna is unreduced and is comparatively more robust than in Merycoidodon. The upper 

 humeral articulation of the sigmoid cavity is smaller in transverse diameter, the lower part of the 

 cavity is broader, and the anteroexternal border of the shaft is more prominent than in the other 

 genus, while the "cuneiform facet has a relatively greater transverse, but somewhat less antero- 

 posterior diameter." The facet is more convex anteroposteriorly, in consequence of which the 

 pisiform articulation is continuous with that for the cuneiform. 



The carpus is similar to that of the older genus, except that while it is almost as broad, it is 

 higher. 



There is nothing to indicate the presence of a pollex. The metacarpals are broad and more 

 flattened, with Mc. V more robust, though somewhat shorter in contrast with Merycoidodon. The 

 phalanges are depressed, as in the latter genus, but are as long or longer, and the terminal ungues 

 are slightly more depressed and broader. 



The border of the acetabulum is much heavier and more rugose, the acetabulum is deeper, and 

 the anterior border curves backward slightly to lock the head of the femur more securely in 

 Phenacocoelus. The femur itself is apparently longer and the tibia proportionately stouter, the 

 cnemial crest overhangs the fibular side of the shaft more markedly, and the tibial shaft has a 

 decided obliquity in the posterofibular direction, in contrast to that of Merycoidodon. The tibia 

 and fibula have a greater transverse diameter distally. 



Of considerable importance is the fact that the pes is broad and short, shorter, in fact, than 

 the manus. This is an unusual character in the merycoidodonts. The metatarsals are unusually 

 heavy and short, more so than the metacarpals. Mt. II is the shortest, with Mt. V next in length, 

 then Mt. Ill, and Mt. IV the longest and heaviest. The phalanges are slightly more depressed and 

 are more expanded laterally than in Merycoidodon. 



Genus TICHOLEPTUS Cope 1878 

 Table 9 



Original Reference: A new genus of Oreodontidas. Amer. Nat., XII, p. 129. 

 Synonym: Brachycrus Matthew 1901. 

 Genotype: Ticholeptus zygomaticus Cope. 



Genoholotype: Cat. No. 8112 A.M.N.H., skull and jaws, joined by matrix, somewhat laterally crushed, 

 and with nasal region damaged. 



Distinguishing Characters: Skull rather high, longer than that of Merychyus (200 mm.- 

 270 mm.), mesocephalic to brachycephalic (indices 0.51—0.67; 0.51 that of the genoholotype); 

 nasal bones relatively shorter than in Merychyus and not extending anterior to the posterior of the 

 canines; brain case rather short, narrow, and high; facial vacuities very small to large and antorbital 

 fossa small, but shallow to deep; orbits small and of medium height; frontals long and moderately 

 wide; exoccipital area broad; malar decidedly deep and zygomatic arches light; bulla; large; 

 dentition moderately hypsodont; superior premolars with apparently no backward slant; anterior 

 part reduced in P 1 " 3 , somewhat crowded, with greater thickening in posterior crescent of P 3 ; M 2 and 

 M 3 showing tendency to be nearer in length than are M 1 and M 2 ; lower premolars not crowded 

 and P 4 bifurcated in anterior part; lower molars increasing in length, with M 3 double that of Mi; 

 neck short; legs and feet of medium length and weight; four toes on all feet; body of medium 

 length. 



Discussion: In this genus the length from M 3 to and including the occipital condyles is 

 approximately the same as that from and including M 3 to the posterior edge of the canine. In 

 Merychyus the latter dimension is often the greater. 



It seems as if there were too many species in this genus, especially as a majority of them were 



