Ancient Vegetation of the Earth. 321 
plation of the diversified shrubs and plants which fringe the bor- 
ders of our forests, or adorn our meadows, and of which the 
flowers exhibit to us almost all the tints of the prism. Finally, 
there result from this diversity of.structure, among these plants, 
many varieties suited to the nourishment of man or of animals ; 
and indeed such as are’ even indispensable to their existence. 
The variety in the organization and aspect of the vegetables 
which at present cover our globe is indicated by the number of 
_hatural groups into which they are capable of being divided. 
These groups or natural families amount to more than two hun- 
dred and fifty, of which about two hundred belong to the class 
of the Dicotyledons, (which consequently present the greatest 
variety of structure,) and thirty to that of the Monocotyledons. 
Now the first of these classes, that is, the two hundred families 
which they contain, are completely wanting in our primitive 
flora, and seldom can we there recognize any indications of the 
Monocotyledons. 
The class which constituted, almost alone, the vegetation of 
this primitive world is that of the vascular Cryptogamia, which 
at present comprehends no more than five families; almost all of 
which had parallels in the ancient world; such are the Ferns, 
Equiseta and Lycopodiz. ‘These families constitute, thus to 
speak, the first degree of ligneous vegetation : they present, like 
the arborescent Dicotyledons or Monocotyledons, trunks more or 
less developed, of a solid texture, although more simple than 
those of these trees, and garnished with numerous leaves; but 
they are deprived of those reproducing organs which constitute 
the flowers, and they present, in place of fruit, organs much less 
complicated. 
These plants, so simple, so little varied in their organization, 
and which, by their number and dimensions, rise not above a 
very inferiour rank, in our present vegetation, constituted, in the 
dawn of the creation of organized beings, almost the entire vege- 
table kingdom, and formed forests so immense that we find not 
their analogy in modern times. The rigidity of the leaves of 
these vegetables, the absence of fleshy fruits and farinaceous 
seeds, would have rendered them very unfit to have served as 
alimént to animals: but terrestrial animals, at the time of their 
growth, had not yet existence ; the seas alone offered numerous 
Vou. XX XIV.—No. 2 Al 
