LIFE 



463 





Fig. 400. One of the Cycadofilires, Lyglnodendron oldhamia, (Restoration 

 by D. H. Scott and J. Allen.) 



feet and a width of six inches. They are preserved in great abun- 

 dance, and make up a large part of some beds of coal. In one form, 

 the leaf had a distinctly fleshy character, as if adapted to xerophytic 

 (dry) life. The floral organs were peculiar to the family, and have 

 been worked out with marvelous success, even the structure of the 

 pollen having been determined. 



Conifers have not been found in the Pennsylvanian rocks, but 

 the vegetation of the uplands, where conifers probably would have 

 lived, is not known. 



Climatic Implications of the Coal-plants 



What suggestions do the Coal-plants give relative to the atmos- 

 pheric conditions under which they grew? Two partly antagonistic 

 views relative to these conditions have been held. The one regards 

 the beds of coal as evidence of a very luxuriant growth of vegeta- 

 tion, which in turn has been thought to imply a warm, moist atmos- 

 phere, heavily charged with carbon dioxide. The great size of 



