THEORY OP THE EARTH. 107 



finally, that all these enumerated circumstances 

 are often united in the same species of animal. 



It is quite impossible to assign reasons for these 

 relations ; but we are certain that they are not 

 produced by mere chance, because, whenever a 

 cloven-hoofed animal has any resemblance in the 

 arrangement of its teeth to the animals we now 

 speak of, it has the resemblance to them also in the 

 arrangement of its feet. Thus camels, which have 

 tusks, and also two or four incisive teeth in the up- 

 per jaw, have one additional bone in the tarsus, 

 their scaphoid and cuboid bones not being united 

 into one ; and have also very small hoofs, with cor- 

 responding phalanges, or toe-bones. The musk 

 animals, whose tusks are remarkably conspicuous, 

 have a distinct fibula as long as the tibia ; while 

 the other cloven-footed animals have only a small 

 bone articulated at the lower end of the tibia, in 

 place of a fibula. We have thus a constant mutual 

 relation between the organs or conformations, 

 which appear to have no kind of connexion with 

 each other ; and the gradations of their forms in- 

 variably correspond, even in those cases in which 

 we cannot give the rationale of their relations. 



By thus employing the method of observation, 

 where theory is no longer able to direct our views, 

 we procure astonishing results. The smallest frag- 

 ment of bone, even the most apparently insignifi- 

 cant apophysis, possesses a fixed and determinate 



