UNGULATA. 317 



Fio. 180. 



Feet of Ungulata Litopterna from the Santa Cruz Formation (Lower Tertiary) 

 of Patagonia. (After Ameghino.) 



A, B. Theosodon lydekkeri ; right fore and hind feet, one-third nat. 

 size. 



C. Proterotherium intermixtum ; right fore foot, one-third nat. size. 



D, E. Thoatherium cr epi datum ; left fore and hind feet, one-third nat. 

 size. 



a, astragalus ; c, calcaneum ; c 2 , c 3 , middle and external cuneiform ; 

 cb., cuboid ; c/., facette for fibula on calcaneum ; en. , cuneiform ; lu., lunar ; 

 m, magnum; n, navicular ; sc., scaphoid; td., trapezoid; un., unciform. 

 B, radius ; u, ulna ; i v, numbers of digits. 



