THE CHAIN OF LIFE TRACED BACKWARD 1 3 



know as yet very little of animal life. We may 

 therefore take the Lower Cambrian, or "Olenellus 

 Zone" as it has been called from one of its more 

 important crustaceans/ as our starting - point for 

 plunging into the depths below. In doing so, we 

 may remark on the orderly and symmetrical nature 

 of the chain of life, and on the strange fact that 

 for so long ages animal life seems to have been 

 confined to the waters, and to have undergone little 

 development toward its higher forms. It is like a 

 tree with a tall branchless stem bearing all its 

 leaves and verdure at the top, or like some ob- 

 scure tribe of men long living in isolation and 

 unknown to fame, and then, under some hidden 

 impulse or opportunity, becoming a great conquer- 

 ing and dominant nation. Or to compare it with 

 higher things, it is like the Christian religion, for 

 ages confined to a small and comparatively un- 

 important people, and developing slowly its faith 

 and hopes, and then suddenly, under the personal 

 influence of Christ and His apostles, spreading itself 

 over the world, and in a few centuries becoming 

 the ruling power in its greatest empire, surviving 



* See figure, p. 20. 



