370 



MECHANICAL EVOLUTION. 



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

 Similar evidence is furnished by the genus Anoplotherium* of the 

 French Eocene. Its posterior foot is modified artiodactyle, while 

 the anterior is modified perissodactyle. We may assume from 



v«y 



Fig. 72. Fio. 73. 



Fig. 72. — Right posterior foot of Protohippus sejundus Cope, from Colorado, about 

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



Fig. 73. — Right posterior foot of Fo'ebrotherium labiatutn Cope, from Colorado, three 

 fifths natural size. From Hayden's Report, 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. 



* Eurytherium Gorv. in the original, a name shown by Schlosser to apply to 

 Anoplotherium. (Ed. 1886.) 



