366 M. Brongniart on the Vegetation of 



surface of the globe ; and we can, with much probabihty, deduce 

 from it, that the extent of the continents, the temperature and the 

 nature of the atmosphere, differed but very little from what at 

 present obtains. I am far from asserting, however, that things 

 were then precisely as they are now ; the results of geological and 

 zoological investigation would entirely contradict such supposi- 

 tion. Thus, the continents were certainly of less extent than they 

 now are, as the marine deposites of that epoch indicate that the 

 sea covered them in part. The temperature was probably higher, 

 for the nature of the animals of this same period indicates a 

 warmer climate, but the general characters of the vegetation were 

 the same. The same classes, in the same proportions — the same 

 genera, and often closely allied species, existed at this epoch, and 

 still exist. It may therefore be said that the vegetable kingdom 

 was invested with the same forms as those which it now presents, 

 and that it was subjected to a similar mode of distribution. 



The study of the metamorphoses of the vegetable kingdom, if 

 I may employ the expression, during the formation of the crust 

 of the globe, seems therefore to announce, that the temperature 

 and extent of the seas have always gone on diminishing, from 

 the first appearance of vegetables upon the earth to the present 

 epoch. 



The comparison of the successive developements of vegetables 

 and animals, is not one of the least remarkable parts of the study 

 of these fossil organized bodies. 



It is known, in fact, that, in the older deposites, or those of the 

 same epoch as the coal formation, there exist no remains of land 

 animals ; while at that epoch the vegetation had already assumed 

 a great dev elopement, and was composed of plants, as remarkable 

 for their foims as for their gigantic size. 



At a more advanced period the terrestrial vegetation loses, 

 in a great measure, this singular developement, and the cold- 

 blooded vertebrate animals become very numerous. This state 

 of things is what is observed during our third period. 



Lastly, the vegetables become more diversified and more per- 

 fect, but those which resemble the plants that have first existed 

 are reduced to a much smaller size. This is the epoch of the 

 appearance of the most perfect animals, those which respire in 

 air, the mammifera and birds. 



