XXXIIl] 



DADOXYLON 



259 



Dadoxylon permiense (Renault). 



This Permian species from Autun^ differs from typical examples 

 of the genus in the differentiation of the pith into a central thin- 

 walled region contracted into transverse diaphragms surrounded 

 by a cylinder of stouter tissue and in the greater breadth of the 





Fig. 476. Dadoxylon Pedroi. 

 of the secondary wood, 

 wood. (After ZeiUer.) 



A, transverse section showing the pith and part 

 B, longitudinal section of part of the secondary 



medullary rays. The tracheids have 3 — 4 rows of pits of the 

 usual type. Spirally disposed, decurrent, leaf-bases occur on the 

 surface of the stem, and the cortex includes secretory canals and 

 strands of hypodermal stereome. A small number of veins pass 

 up the median part of the lamina which in this respect and in its 



' Renault (96) A. p. 350; (93) A. PI. Lxxvn. 



17—2 



