Marsh — A New Order of Extinct Mammals. 447 



The fore limbs were somewhat shorter than those behind. 

 The humerus is stout, of moderata length, with its distal end 

 much flattened, and a supracondylar foramen. It resembles 

 the humerus of a carnivore rather than that of an ungulate. 

 The radius and ulna are nearly equal in size. The head of the 

 radius is expanded transversely, and closely applied to the ulna, 

 indicating but little rotation. The ulna is a stout bone, with 

 the distal end compressed and pointed. The carpal bones 

 resemble in general form and position those of Hyrax, and a 

 central bone is present in the same place as in that genus. 

 The five metacarpal bones are all well developed, and their 

 position with reference to the carpals that support them is 

 shown in the fore foot of Hyracops represented below in 

 figure 1. 



Figure 1. — Left fore foot of Hyracops socialis, Marsh. 

 Figure 2. — Left hind foot of same species. Both natural size. 



a, astragalus ; c, calcaneum ; cb, cuboid ; ce, central bone ; I, lunar ; m, magnum ; 

 n, navicular ; p, pisiform ; B, radius ; s, scaphoid ; td, trapezoid ; tm, trapezium ; 

 U, ulna ; u, unciform ; x, epicuneiform. 



