Value of Geological Formations. 33 



at the earliest sports of animals, and at the first bursting 

 forth of vegetation ; we behold animated nature issuing from 

 the hand of th« Creator. And if we can hope one day to 

 arrive at the knowledge of the general plan of creation, it 

 is by attentively investigating even the faintest appreciable 

 relations between ancient species, and by following step by 

 step the modifications which organized beings, viewed as a 

 whole, have undergone in all the series of formations, from 

 one to another, up to our own times. 



There is one kind of comparison which has been too much 

 neglected in our attempts to estimate the importance of the 

 stages of our globe relatively to the remains of the organized 

 beings which they inclose, but which, I am convinced, will 

 one day exercise a great influence on our manner of regarding 

 fossil faunas, by enabling us to determine the value of those 

 assemblages of strata which have been called terrains or 

 geological formations. I allude to the proportions in which 

 we find species of the different classes of the animal king- 

 dom, in given localities, on the present surface of the globe, 

 or in such or such a group of formations. It is evident 

 that it is the beings which now live on the earth that we are 

 best acquainted with, and respecting which, as a whole, we 

 possess, in every respect, the most complete and important 

 information. It is consequently from these beings, or rather 

 from the knowledge we possess of them, that we ought to 

 borrow the terms of comparison for all that relates to the 

 distribution of fossils in the whole formations. It is true that 

 the geographical distribution of living animals is yet but im- 

 perfectly known ; it is sufficiently so, however, to make us 

 aware that all the countries of the globe, considered in a 

 certain extent, have their particular faunas, composed of an 

 assemblage of peculiar species, mingled with others which 

 extend either more to the north or south, east or west ; and 

 that, consequently, each country supports but a small propor- 

 tion of the totality of species which people the surface of the 

 globe. 



When we wish, therefore, to appreciate the value of the as- 

 semblages of fossils which we discover in a formation, and 

 seek to determine the number of species proper to the geolo- 



VOL. XLI. NO. LXXXI. — JULY 1846. C 



