SPECIES. 125 



and circumstances, diffuse around it ; it does not cost us more 

 to admit this than to admit that similar elements have arisen 

 at different periods of time. This last supposition may even 

 be regarded as so much more probable, that we must renounce 

 entirely, in order to explain specific transformations, the influ- 

 ence of the geological revolutions of which Etienne Geoffrey 

 took so much account. We have seen higher up that these were 

 far from being proved; we can add, in support of our asser- 

 tion, a fact which we think has not been sufficiently remarked. 

 If these revolutions ever existed, we have a strong proof that 

 they have only very slightly altered the conditions of life 

 on the surface of the globe, at least since the ancient pe- 

 riods during which the first alluvium was deposited; if we 

 dredge some yards deep in the ocean, the drag brings up 

 terebratulao and encrini; that is to say, animals identical 

 with those which we find in the most ancient alluvia. Is 

 it not remarkable that the lowest placed fossil in the strati- 

 graphic ladder of the beds of the terrestrial surface, the most 

 ancient fossil which we know, is precisely this same terebratula, 

 which still lives in our seas ? What must we hence conclude ? 

 That there once existed on the globe, at least to a certain 

 extent, conditions of aquatic life sensibly identical with those 

 which exist at the present day. 



Whether all the species of vertebrata descend from one 

 original spontaneous beginning, or from many successive ones, 

 signifies very little, since, in the second case, the primordial 

 individual- elements which have thus appeared at various times, 

 would always show a great analogy to one another. 



Now, after all that we have said, this is how we may, in our 

 opinion, represent by a graphic figure the whole of the ver- 

 tebrate kingdom,* in the present and in the past. Let us 

 image a conical figure : the individual- element of which we 

 have spoken will occupy its summit. From this point a num- 

 ber of straight lines, few at first, will start, branching off and 



* Some may be astonished at our applying the word kingdom to the verte- 

 brata. We do so because, in truth, the distance which separates them from 

 other animals seems to us almost as great, and even more decided, than that 

 which separates the invertebrata from plants. 



