﻿244 BRITISH FOSSIL CEPHALOPODA. 



parable to the occasional differentation in some animals of organs considered 

 high in the scale at various stages of its life-history. This theory allows us to 

 account for the rapid progress of life at the first, and its varying progress later, 

 and explains, by the co-adaptation of organs in the animal, the co-adaptation of 

 various animals to each other ; but, above all, it shows an analogy, in the rapid 

 development of particular parts at definite times of life, with the introduction of 

 species on the globe, which, like the material of the organ, have sprung from 

 previously formed material. 



