SKELETON OF THE RHINOCEKOS. 



167 



and each supports three phalanges, the last being provided 

 with a diminutive hoof. In the extinct Palceothena^ the 

 outer and inner digits acquired stronger proportions, and 



Fig. 29. 



SKELETON OF THE RHINOCEROS {BIl. biconiis). 



the entire foot was shortened. The transition from the 

 Palceotheria^ by the extinct hornless rhinoceros {Acerothe- 

 rium), to the existing forms of rhinoceros, is completed. 

 In the skeleton of the rhinoceros, we find resemblances to 

 the horse in the number of the dorsal vertebrae, in the 

 third trochanter of the femur, and in the number of digits 

 on each foot, albeit the two that are hidden and rudi- 

 mental in the swifter quadruped are here made manifest in 

 their full development : the concomitant shortening of the 

 whole foot, and strengthening of the entire limbs, a^jcord 

 with the greater weight of the body to be supported, clad 

 as it is with a coat-armor of thickened tuberculated hide : 

 the broader feet, terminated each by three hoofs, afford a 

 better basis of support in the swampy localities affected 



