THE PENNSYLVANIAN PERIOD 



647 



habit has been inferred. The leaf structure suggests a shady habitat, 

 perhaps one of undergrowth. The class was represented in the 

 Devonian, had its climax in the middle Pennsylvanian, and con- 

 tinued into the Permian and possibly later. 



Fig. 449. Carboniferous Equisetales and Sphenophyllales : a, Catamites 

 cislii; 6 Annularia sphenophylloides; c, Sphenophyllum longifolium. 



The Lycopodiales. This was the master group of the Coal flora, 

 constituting trees of large size and attaining to the highest organ- 

 ization reached by the pteridophytes. From this high estate, they 

 have since fallen to prostrate or weakly ascending plants of moss- 

 like aspect (club mosses and ground pines) . The chief genera were 

 Lepidodendron (Fig. 447) and Sigillaria, of which the former was 

 the earlier and simpler type. Both take their names from the leaf- 

 scars of leaf -cushions (lepidos= scale, sigilla=seal) which the trunks 



