140 EVOLUTION OF LIFE, 
but in still earlier forms, like Coryphodon, Pliolophus, and 
Lophiodon, we find teeth combining the characteristics of 
the Paleotherium and Anoplotherium. So that just as the 
Rhinoceros and Horse are specialized forms of the Paleo- 
therium, the Pig and Sheep of the Anoplotherium, so the 
Paleotherium and Anoplotherium are specialized forms of 
the Coryphodon. Accepting the theory of the specialized 
higher forms of life having descended from a more general 
lower form, we have an explanation of the harmony offered 
by the anatomy, embryology, and petrified remains of 
these animals. But the theory of Evolution explains not 
only the most important facts in reference to this particular 
order of animals, but wé hope to have shown that it is 
equally applicable to the whole vegetal and animal king- 
dom. The question now naturally arises, Are there any 
natural causes sufficient to effect the development of the 
animal and vegetal kingdoms out of a monad? 
To that subject we now turn. 
