in (he different Geological Epochs. 99 



latively to the plants now living on the same ground, are 

 so much greater as they occur in the most ancient beds of 

 these tertiary formations. The most recent indicate a cli- 

 mate differing little from that of temperate Europe ; the 

 most ancient announce a warmer climate than now occurs in 

 that region. 



But in all these beds, which are very recent when com- 

 pared with the other parts of the crust of the globe, we find 

 vegetation, as a whole, agreeing in all its principal features 

 with the mass of the vegetable kingdom which still inhabits 

 the surface of the earth; there are the same classes, the 

 same natural families, often the same genera. The general 

 characters of this extinct vegetation are the same as those of 

 the existing vegetation, and we might suppose ourselves only 

 transported to another quarter of the globs. Viewed as a 

 wliole they are the same ; the details only are different. 



But if, "on the contrary, we descend more deeply into the 

 layers composing the earth's crust, and go back to the more 

 ancient periods of the creation ; if we consider the vegeta- 

 bles preserved in the formations named secondary, which have 

 preceded those of which we have spoken by many ages, we 

 shall find the vegetable kingdom reduced to a much less 

 considerable number of those natural groups which we name 

 families or classes. 



This variety of form and aspect, which gives such a charm 

 to the existing vegetation, did not then exist ; and, to cha- 

 racterise in a word the vegetable kingdom of those remote 

 periods, we may say that the plants composing it, much less 

 varied and numerous than those now covering our ground, 

 were all deprived of what constitutes their greatest orna- 

 ment, namely, those flowers with brilliant envelopes which 

 belong to almost all the plants of our period. All the 

 vegetables of the first geological periods were in fact analogous 

 to°our firs and ferns, whose habit and elegant foliage form 

 all their beauty. 



In these ancient times of geological history, we may far- 

 tlier distinguish two great periods ; the one nearest our own 

 times, during which terrestrial vegetation, almost entirely 

 limited to three families, the ferns, coniferac, and cycades. 



