176 THE MAMMALIA OF THE DEEP RIVER BEDS. 



and the ridge external to that notch is wider in correspondence with the more mesial 

 position of the intercondylar ridge. The process for the attachment of the external 

 ligament is a sharp, compressed ridge, which is not so prominent as the massive 

 tubercle of the prong-horn's radius, and hence the latter, though having a narrower 

 trochlea, measures more across the proximal end than does that of Blastomeryx. 

 The distal end differs little from that of the prong-horn, though owing to the broader 

 shaft it expands relatively less ; on the anterior face is a broad sulcus for the extensor 

 tendons, bounded by sharp ridges, the inner one of which bifurcates near the distal 

 face, forming a second and much narrower sulcus. The carpal facets are very modern 

 in character, except for the less width of the lunar surface, and run very obliquely 

 across the distal face from before backward and mesially ; the scaphoid and lunar 

 facets are separated throughout by a sharp ridge and both are reflected far up upon 

 the posterior side of the radius. As in existing ruminants, the radius has expanded 

 so as to come into contact with the cuneiform, though the facet for that bone is much 

 smaller than in the prong-bnck. 



Nothing is known of the carpus, but it may be inferred from the facets of the 

 radius that the lunar is relatively less expanded than in most existing Pecora. 



The metacarpus (PI. VI, Fig. 50) is in the shape of a well-defined cannon-bone, 

 consisting of the coalesced third and fourth metacarpals ; no trace of the laterals 

 (ii aud v) is preserved, but they were nevertheless probably present in very reduced 

 form, as may be confidently inferred from the condition in Cosoryx. The cannon- 

 bone is considerably shorter than that of the prong-buck, is distinctly stouter and 

 of quite different shape. In AniilocafAXi, Cosoryx and Blastomeryx gemmifer the 

 proximal end is much compressed in the antero-posterior direction, but in B. antilo- 

 jrinus this compression is slight, the transverse diameter but little exceeding the 

 fore-and-aft. The latter diameter diminishes steadily towards the distal end, increas- 

 ing slightly above the phalangeal trochlea; the groove on the posterior face of the 

 shaft is deeper in its proximal portion than in the prong-horn, but is not continued so 

 far down. As in the ruminants generally, the distal venous foramen on the anterior 

 face is extremely small. The trochleas for the phalanges are somewhat lower than in 

 most existing Pecora, but the carinas are complete, extending over the entire dorsal 

 face of the trochleas. 



No phalanges are associated with the specimen. 



Measurements. 



B. ANTILOPIKUS. A. AMERICANA. 



M. IT. 



Humerus, breadth of distal end 041 .033 



Humerus, depth of shaft above aneoneal fossa 023 .017 



