THE LAW. 



HAVING reviewed in detail the life-phases of the successive 

 epochs of geology, we now proceed to a few generalisations 

 respecting the advent and exit the rise, progress, and de- 

 cay of specific vitality. In so doing, we shall endeavour 

 to give expression to some of the leading laws which seem 

 to have influenced Life since its first appearance on the ter- 

 raqueous globe, believing that details are of themselves 

 comparatively worthless unless we can co-relate and con- 

 nect them into something like order and system. I am 

 fully aware, where so much of our evidence is merely nega- 

 tive, and where more, perhaps, is still fragmentary and im- 

 perfect, that any attempt of this kind may be thought 

 premature and perhaps presumptuous. But the law of our 

 nature, like the law of creation, is ORDER ; and the mind 

 instinctively groups and associates, and tries to connect ef- 

 fects with their causes, the moment it turns itself to any 

 new field of research. And so, in Paleontology, these 

 generalisations, however tentative and temporary, serve as 

 centres round which to marshal new facts, and help to 

 give consistency and interest to what might otherwise ap- 

 pear a mass of discordant and repulsive details. And grant- 

 ing that many of these generalisations may be set aside by 

 future discoveries, so long as they are received in the same 

 spirit in which they are submitted, they cannot retard the 



