ANCIENT PLANTS 



Fig. 3. — Cast of the Leaf Bases of Lefidodendron, showing finely marked detail. (Photo.) 



Stem remains 



Fig. 4. — " Sternbergia. ' ' 

 Internal cast of the stem 

 of Cordaites. 



as a solid stone. Where this has hap- 

 pened, and the outer part of the plant 

 has decayed so as to leave no trace, 

 the solid plug of stone from the centre 

 may look very much like an actual stem 

 itself, as it is cylindrical and may have 

 surface markings like those on the out- 

 sides of stems. Some of the casts of 

 this type were for long a puzzle to the 

 older fossil botanists, particularly that 

 illustrated in fig. 4, where the whole 

 looks like a pile of discs. 



The true nature of this fossil was 

 recognized when casts of the plant 

 were found with some of the wood 

 preserved outside the castings; and 



