106 THEORY OF THE EARTH. 



cates to the observer the forms of the teeth, of the 

 jaws, of the vertebrae, of all the leg-bones, thighs, 

 shoulders, and of the trunk of the body of the ani- 

 mal which left the mark. It is much surer than all 

 the marks of Zadig. Observation alone, indepen- 

 dent entirely of general principles of philosophy, 

 is sufficient to show that there certainly are secret 

 reasons for all these relations of which I have been 

 speaking. <v fi 



When we have established a general system of 

 these relative conformations of animals, we not 

 only discover specific constancy, if the expression 

 may be allowed, between certain forms of certain 

 organs, and certain other forms of different organs ; 

 we can also perceive a classified constancy of con- 

 formation, and a correspondent gradation between 

 these two sets of organs, which demonstrate their 

 mutual influence upon each other, almost as cer- 

 tainly as the most perfect deduction of reason. 

 For example, the masticatory system is generally 

 more perfect in the non-ruminant hoofed quadru- 

 peds than it is in the cloven-hoofed or ruminant 

 quadrupeds ; as the former possess incisive teeth, 

 or tusks, or almost always both of these, in both 

 jaws. The structure also of their feet is in general 

 more complicated, having a greater number of toes, 

 or their phalanges less enveloped in the hoof, or a 

 greater number of distinct metacarpal and metatar- 

 sal bones, or more numerous tarsal bones, or the 

 fibula more completely distinct from the tibia : or, 



