1889.] '±^0 [Cope. 



behind bj' a groove, as in the horse. The superior grooved boundary of 

 the internal condylar face is better defined. The ulnar and radial shafts 

 are coiissified, but the head of the radius is not united with the ulna, 

 though in contact. Distad to this contact, is a considerable interosseous 

 space, relatively longer than in the horse. The line of contact of the 

 head of the radius is convex downwards in the middle. Olecranon much 

 compressed. The carpal articulation of the radius is like that of the horse. 

 The scapho-lunar ridge is transverse ; the scaphoid surface recurved be- 

 low, and a fossa behind the lunar surface. The convex superior sur- 

 face of the bone has five facets, two of which are more or less lateral. 



The left metacarpus and os magnum are preserved ; the magnum has a 

 relativel}' smaller transverse diameter than in the horse ; its posterior tuber- 

 osity is also narrower. The facets of the inter side are much less pro- 

 nounced than in the horse, the whole being divided by an anteroposterior 

 groove. On the internal side the two anterior or trapezoid facets areas 

 large as in the horse, while the posterior facet of the recent animal is ab- 

 sent from the H. speciosum. The magnum facet of the metacarpal is unin- 

 terrupted, not divided, as in the horse. The two unciform facets are much 

 more oblique than in the horse. The trapezoides differs considerably from 

 that of the horse. It has but one facet below, and that one is continuous 

 with that of the metacarpal. It sends posteriorly a hook-like process. 

 Above, it encloses no foramen with the magnum. The bevels for the lateral 

 metacarpals are distinct throughout the bone. The posterior face is divided 

 distally hy a median obtuse ridge into two shallow gutters, a character not 

 seen in the horse. There is no trace of the trochlear keel on the anterior 

 face of the distal extremity. The section of the shaft at the middle is at 

 least a semicircle. The phalanges of the middle toe have the form usual 

 among these animals. They are rather more slender than in some of the 

 allied species, as H. isonesum, and the proximal inferior triangular surface 

 is more produced, reaching to the end of the proximal two-fifths of the 

 length. It forms a large triangular face, concave in the middle. 



Measurements of Fore Limb. M. 



Diameters of f anteroposterior at inner side 045 



humeral condyles S " at middle 021 



(^ transverse 040 



Depth of ulna at edge of head of radius 019 



Distal width of radius 0:!8 



" depth of radius (greatest) 034 



T^. . ~ 1 -J f .(anteroposterior 016 



Diameters of scaphoid facet < * „,„ 



f transverse Oio 



Diameters of lunar facet. . . \ anteroposterior 014 



c transverse 016 



( anteroposterior .023 



Diameters of os magnum. . J transverse 023 



(_ longitudinal Oil 



