644 



GEOLOGY 



great divisions of this group were present, and all of them were 

 nearly or quite at their climax. An attempt is made to represent 

 their general aspect in Fig. 447. Of lower plants, little is known. 



The most rapid evolution of floras was perhaps in the Pottsville 

 epoch. Half the genera of that epoch scarcely survived it, and few 



Fig. 447. A composite group of leading Carboniferous plants, adapted 

 from restorations by various paleobotanists, by Mildred Marvin. In 

 the foreground at the right, Lepidodendron; at the left Sigillnrin: in 

 the right center rear, a tree fern; in the left center rear, CordniU*-, at 

 the extreme right and left, Catamites. 



of them lived after the Allegheny epoch. This was pre-eminently 

 the stage of CycadoJUices, Sphenopteris, Neuropteris and Alcthop- 

 teris, and of the great tycopod types. The early Pennsylvania 

 floras were widely distributed. Thus three floras in Asia. Minor 

 may be correlated severally with three floras from the Pottsville 



