384 



HISTORICAL GEOLOGY 



group or of that transitional class which we have called the 

 seed ferns (p. 293). There is still no evidence of the existence 

 of the plants with incased seeds and prominent flowers, but 



FIG. 404. Ideal view of the trees in a Carboniferous swamp. The large 

 cone-bearing tree in the center is the scale tree (Lepidodendron). On the 

 right are gigantic horsetail reeds and on the left Cordaites, one of the ear- 

 liest Gymnosperms. (After Horsfall.) 



