THE THEORY OF NATURAL SELECTION. 305 



toe (or third toe) of an ordinary quadruped. If the 

 skeleton of the horse's foot be examined, it will be seen 

 that lying by the side of the great middle toe are two 

 little splint-like bones, one on each side, which are the 



FEET OF FOSSIL EQUID^E. 



'rudiments' of the index (or second) toe, and the ring toe 

 (or fourth toe). The horse, therefore, possesses a foot with 

 one complete toe and two incomplete ones; the outer- 

 most toe (the little or fifth toe), and the innermost toe 

 (the thumb or great toe, or first toe) having no repre- 

 sentatives at all. If, however, there be any truth in the 

 general doctrine of evolution, it may be taken as certain 

 that the horse has descended from a five-toed ancestor, 

 since the typical Mammals possess five digits to the foot. 

 Through the researches of Gaudry, Marsh, and others, it 

 may now be confidently asserted that the horse has 

 descended from a five-toed form. Thus, we meet with a 

 number of horse-like animals, all now extinct, in which we 



find the foot, as we trace them backwards into the past, to 



T 



