592 



GEOLOGY. 



places, semi-terrestrial algae were present in great abundance, but 

 for obvious reasons their record is obscure. Regnault has identified 

 bacteria. 



It was emphatically the period of the Pteridophytes, and their 

 deployment in numbers, size and grade of organization was very remark- 

 able. There were true ferns, transitional ferns, and fern-like gym- 

 nosperms; there were horsetails in the form of calamarians, spheno- 

 phylls in typical development, and gigantic lycopods in the form 

 of lepidodendrons and sigillarias, or, in more technical terms, there 



Fig. 275.- — A composite group of leading Carboniferous plants adapted from restora- 

 tions by various paleobotanists by Mildred Marvin. In the foreground at the 

 right, Lepidodendron; at the left Sigillaria; in the right center rear, a tree fern; 

 in the left center rear, Cordaites, at the extreme right and left, Catamites. 



were Filicales, Cycadofilices, Equisetales, Sphenophyllales, and Lyco- 

 podiales, all the great divisions of the group, and all of these were 

 nearly or quite at their climax, and some of them were verging into 

 other types. An attempt is made to represent their general aspect 

 in Fig. 275. 



