190 BOTANY. [chap. vi. 



Lyeopodiacece. 



The club-mosses are contemporaneous in their appear- 

 ance and period of maximum development with the 

 Equisetacese, and like the latter assumed large dimen- 

 sions and formed forests during the Carboniferous age, 

 their remains contributing largely towards the forma- 

 tion of coal. At the present day the remaining members 

 of the group are few and of small size. 



From the above it will be seen that all the groups of 

 Cryptogams attained their maximum of development 

 during the primary epoch, and mostly during the 

 Carboniferous period, which on this account has been 

 termed the age of Cryptogams. Several orders that 

 during that period formed extensive forests, as the 

 species of Sigillaria, Lepidodendron, Oalamites, etc., 

 have long ago become extinct. 



Phaneeogams. 



Gymnosperms. 



OowiferoB. 



Conifers, the earliest of Phanerogams, first occur in 

 the Devonian rooks, their maximum extending through 

 the mesozoic period, after which a decline took place 

 that has continued up to the present time. 



GyeadacecB. 

 The Cycads appear in limited numbers in the Carboni- 

 ferous age, suddenly attain a wide-spread maximum 

 during the Jurassic period, of which they are highly 



