370 



MECHANICAL EVOLUTION. 



is perissodactyle, all the digits but the third being rudimental ! 

 Similar evidence is furnished by the genus Anoplotlierium * of the 

 French Eocene. Its posterior foot is modified artiodactyle, while 

 the anterior is modified perissodactyle. We may assume from 



Fig. 72. Fig. 73. 



Fig. 72. — Right posterior foot of ProtoTiippug sejunctus Cope, from Colorado, about 

 one half natural size. From Eeport U. S. Geol. Surv. Terrs. F. V. Hayden, iv. 



Fig. 73. — Eight posterior foot of Foehrotherium labiatum Cope, from Colorado, three 

 fifths natural size. From Hajden's Eeport, iv, PI. cxv. 



these facts, that the posterior foot is more subject to the influ- 

 ences which tend to produce the bidigital structure than is the 

 anterior limb. 



* Euryiherium Gerv. in the original, a name shown by Schlossev to apply to 

 Anoplotherium. (Ed. 1886.) 



