OF EVOLUTION. 



a type of higher or more complicated organization 

 invariably followed a lower type belonging to the 

 same group, but as a general rule we note that 

 there has been a steady advance in type structure. 

 What is the nature of this advance, or the essence 

 of the first required proof? 



Looking at the animal kingdom broadly, and 

 without attempting to destroy the perspective by 

 inquiring into unnecessary details, we find that of 

 the two great divisions into which that kingdom is 

 divided, the backboned or vertebrate animals, like 

 the fish, reptile, amphibian, and quadruped, and 

 those without backbone, the Invertebrata, like the 

 coral, starfish, crab, etc., only the latter is rep- 

 resented in the earliest period, the Cambrian, 

 in which indisputable animal remains have been 

 found. Not a vestige of any of the higher forms 

 has here been met with. But let me warn 

 you against this non-appearance. It is by no 

 means impossible, or indeed unlikely, that back- 

 boned animals already lived during this period of 

 time, and that their remains will still some day be 



