462 THE CAUSES OF THE xi 



pigeons, for example ; you have the dove-cot 

 pigeon, which closely resembles the rock pigeon, 

 from which they all started, existing at the same 

 time with the others. And if species are developed 

 in the same way in nature, a primitive stock and 

 its modifications may, occasionally, all find the 

 conditions fitted for their existence ; and though 

 they come into competition, to a certain extent, 

 with one another, the derivative species may not 

 necessarily extirpate the primitive one, or vice 

 versd. 



Now paleontology shows us many facts which 

 are perfectly harmonious with these observed 

 effects of the process by which Mr. Darwin sup- 

 poses species to have originated, but which appear 

 to me to be totally inconsistent with any other 

 hypothesis which has been proposed. There are 

 some groups of animals and plants, in the fossil 

 world, which have been said to belong to " persist- 

 ent types," because they have persisted, with 

 very little change indeed, through a very great 

 range of time, while everything about them has 

 changed largely. There are families of fishes 

 whose type of construction has persisted all the 

 way from the carboniferous strata right up to the 

 cretaceous ; and others which have lasted through 

 almost the whole range of the secondary rocks, 

 and from the lias to the older tertiaries. It is 

 something stupendous this to consider a genus 

 lasting without essential modifications through all 



