178 



THE MAMMALIA OF THE DEEP EIVEK BEDS. 



copra, tapering less towards the free end. The sustentaculum, fibular and calcaneal 

 facets present no noteworthy peculiarity. 



As in the Pecora generally, the cuboid and navicular are coossified ; the com- 

 pound bone is somewhat broader and of about the same vertical height as in the 

 prong-horn. The distal facets on the cuboid portion are quite different from those 

 of rdloeomeryx furcatus as figured by Fraas (ISTo. 16, PI. VIII, Fig. 12) ; the surface 

 for the main part of mt. iv is broader, especially in front, while that for the posterior 

 hook of the same metatarsal is very much smaller. 



The length of the hind cannon-bone cannot be determined, as none of the speci- 

 mens are complete. It is evident, however, that it exceeded the fore cannon-bone in 

 this respect more than is usually the case in the prong-horn. The proximal end is 

 of subquadrate shape, the breadth and depth of the head being nearly equal and of 

 the same dimensions as in the specimen of Antilocapra which has been employed for 

 comparison. The hind cannon-bone clearly shows that the portion which articulates 

 ■with the entocuneiform is the rudiment of the second metatarsal ; mt. v is probably 

 represented also, but this is not so obvious. The proximal portion of the shaft is 

 narrow and deep ; the groove on the anterior face is strongly marked and terminates 

 distally in a large venous foramen. 



Measurements. 



B. ANTILOFINUS. A. AMERICANA. 



M. M. 



Femur, length (est.) .252 .223 



Tibia, length 256 .256 



Tibia, depth of proximal end 046 .041 



Tibia, depth of distal end 037 .033 



Tibia, width of distal end 034 .030 



Astragalus, length 039 .032 



Astragalus, width of distal end 024 .021 



Calcaneum, length 084 .075 



Calcaneum, length of tuber calcis 051 .045 



Cubo-navicular, breadth 030 .027 



Cuboid, height 016 .017 



Hind cannon-bone, width of proximal end 025 .025 



Hind cannon-bone, depth of proximal end 024 .024 



Restoration. In general appearance and size Blastomeryx antilopinus must have 

 been very like the existing American antelope. The simple, straight and erect horns 

 constitute one striking difference between the two species, and the fossil animal had 

 heavier limbs, lacking the extreme lightness and elegance which are so characteristic 

 of the prong-horn. In the latter the fore and hind legs are of nearly equal length, 

 while in Blastomeryx the hind limbs must have been considerably longer than the 

 fore. The differences are, however, less obvious than the resemblances. 



