36 



THE MAMMALIA. 



On the other hand, the five-toed limb extends from 

 the salamander to man. Together with this we 



have the most 

 various kinds of 

 disappearances 

 and. coalescings 

 till we reach the 

 one-toed foot of 

 the horse, and 

 find, in fact, 

 that a diminu- 

 tion in the num- 

 ber of fingers 

 and toes takes 

 place ; never do 

 we meet with 

 a restoration 

 after the de- 

 crease, and 

 never with an 

 addition to the 



FIG. 1. Eight hand of a river tortoise, number of toes. 



Nat. size. T ^ 



In order to 



illustrate the fundamental form, which we shall 

 follow in its most varied and interesting changes, 

 let us take the right hand of a fresh-water tortoise 



