SKELETON AND TEETH 



91 



An animal is said to be unguli- 

 grade when the weight is carried 

 entirely upon the hoofs and is 

 used only of hoofed animals ; ex- 

 amples are the horses, pigs, deer, 

 antelopes, oxen, etc. The so- 

 called ''knee" of a horse is really 

 his wrist and the ''hock" is the 

 heel, so that the feet make nearly 

 half the apparent length of the 

 legs. Certain very large and 

 massive animals, such as the rhi- 

 noceroses and elephants, are un- 

 guligrade in a modified sense ; 

 the foot is a heavy column, seem- 

 ingly a part of the leg, and the 

 weight is borne upon a great pad 

 of elastic tissue, with the hoofs 

 disposed around its periphery. A 

 very peculiar mode of locomotion 

 is exemplified by certain of the 

 Edentata, in the forefoot of the 

 existing Ant Bear (Myrmeco- 

 phaga juhata) and in both ex- 

 tremities of some of the later 

 representatives of the extinct 

 tground-sloths, or fGravigrada. 

 Here the weight is carried upon 

 the outer edge of the foot, the 

 palm and sole being turned in- 

 ward. No term has been sug- 

 gested for this very exceptional 

 gait, which is a modified form 



Fig. 43. — Left pes of PatagonianDeer 

 (Hippocamelus bisulcus), showing the 

 unguligradegait. T., tibia. jF., lower 

 end of fibula (malleolar bone). Cal., 

 calcaneum. As., astragalus. N.Cb., 

 coossified cuboid and navicular. Mt. 

 Ill, Mt. IV, cannon-bone, formed by 

 the coossification of the thiid and 

 fourth metatarsals. V., Rudimen- 

 tary fifth digit. 



of plantigradism. 



