CALAMODENDRON 35 



In fact, the principal rays are here much more complex 

 in structure than the wood itself. The Calamodendron 

 stems are especially characteristic of the Upper Coal- 

 measures and Permian of Central France. 



This brings us to the question of nomenclature, on 

 which I must say a word. Brongniart, in his earlier 

 works, placed all the Calamitean stems then known to 



J * J" mr f 



Y \ V. 



f 1G. 10. — Calamodendron intermedium. Part of transverse section of stem, showing inner 

 portions of two vascular bundles, with secondary wood. /, pith ; /.r, protoxylem 

 in canals of the bundles ; jr, fascicular wood, containing secondary rays ; f, prosen- 

 chymatous parts of principal medullary rays ; ;«;-, central parenchymatous portion of 

 each ray. .Magnified. After Renault. 



him in the one genus Calamites, and believed them 

 to be related to the Equisetaceae ; subsequently he 

 investigated specimens with the internal structure pre- 

 served, and in all clear cases of the kind he found a 

 well-developed secondary wood. Wherever he found 

 this, he thought he must have to do with a Dicoty- 

 ledonous flowering plant of Gymnospermous affinities, 

 for in those days Gymnosperms were usually included 



