Geological Distribution of Fossil Plants. 287 



stems of these plants, whose internal structure has been, 

 preserved. These specimens have proved that the Sigillarias, 

 the Stigmarias, and probably most of the Calamites, are not 

 plants approaching the Ferns, the Lycopodiums, or the Equi- 

 setaceae, but are special families of the group of Dicotyledonous 

 Gymnosperms, most nearly resembling the Coniferae and the 

 Cycadeae. 



Thus, at the epoch of the coal-deposits, the vegetation 

 must have consisted solely, or almost solely, of two of the 

 great branches of the vegetable kingdom ; the Acrogetioas 

 Cryptogams represented by the herbaceous and arborescent 

 ferns (the latter reduced to the true Caulopteris\ by the 

 Lepidodendrons, a family approaching to the Lycopodiacew, 

 and by some Equisetacece; and the Dicotyledonous Gymnosperms^ 

 including the Sigillariw {Sigillaria^ Stigmaria^ Lepidofloyos)^ 

 the Cala/mitacece (Calamites)^ the Conijeroe {iralcliia)^ and 

 -j^vohdi^Siy ihQ Asterophyllece {Asterophyllites, Annularia, Sphe- 

 fiophylliim.) We thus see the importance this last mentioned 

 division of the vegetable kingdom seems to have had at a re- 

 mote epoch, while we know how limited it is in the vegetation 

 of the present day. 



2. General Summary of the Families and Species of Fossil Plants 

 occurring in the different formations. By M. Gobppert. 



No statement has been published since 1828 of the number 

 of the known species of fossil plants. M. Adolphe Brongniart. 

 enumerated 500 species in his classical work. This number 

 is now nearly quadrupled ; for I myself am acquainted with 

 1792, which belong to 61 families, and 277 genera. I men- 

 tioned 253 species of ferns in the monograph on that family, 

 which I published in 1836 ; but I am now acquainted with 

 more than 524 species. If, without exaggerating, we estimate 

 the known number of species of living plants at 80,000, the 

 fossil Flora, so far as it has been ascertained, amounts to ^ 

 of the living Flora. 



The 1792 fossil species are distributed in the following 

 manner in the different formations : — 



