Ancient Vegetation of the Earth. 319 



But the study of the impressions of stems, leaves, and even 

 fruit, which are in general contained, in so great quantities, in 

 these rocks, proves not only the vegetable origin of this substance, 

 but even enables us to determine the nature of the vegetables of 

 which it has been formed, and which, consequently, at the period 

 of such formation, occupied the surface of the earth. 



Among these vegetable imprints, the most frequent are those 

 produced by the leaves of the Ferns ; yet these Ferns of the prim- 

 itive world are not those which now grow in our climates ; for 

 Europe, at this time, does not produce more than from thirty to 

 forty species, while the same regions then nourished more than 

 two hundred, all much more analogous to those now found be- 

 tween the tropicks than to those of the temperate climates. 



In addition to the leaves of Ferns, the same earths contain 

 trunks, the dimensions of v/hich render them comparable to the 

 most gigantick trees of our forests, while their form is wholly 

 dissimilar ; and indeed all the ancient naturalists, struck with this 

 dissimilarity, and yet desiring to find analogous productions still 

 existent, referred them to arborescent vegetables, then imperfectly 

 known, as the Bamboos, Palms, and the great Cactus, sometimes 

 designated Torch-thistle. But a more attentive comparison of 

 these products of the equinoctial regions with those trunks, the 

 growth of the ancient world, suffices to dissipate all relations, 

 which are founded only on some resemblances in the general as- 

 pect, that have been attempted to be established between them ; 

 and a more profound examination, either of these trunks or of the 

 leaves which accompany them, readily shows that the vegetables 

 which formed these primitive forests are not identical with any 

 trees still found flourishing upon the earth. 



The arborescent Ferns which, by the elegance and magnitude 

 of their exteriour, now form one of the principal ornaments of the 

 equatorial regions, are the only arborescent vegetables which are 

 recognized, even in small number, among the trees of this antique 

 vegetation. 



As to the other fossil stems, remains of these primitive forests 

 of the ancient world, it is among the most humble vegetables of 

 our epoch that we must seek their analogues. 



For instance, the Calamites, which attained from four to five 

 metres (a little more than 13 to 16 feet) of height, and from one 

 to two decimetres (not quite four to eight inches) of diameter^ 



