1 64 STUDIES IN FOSSIL BOTANY 



member was so insignificant that the continuity of the 

 main ring was never interrupted, a group of its more 

 external tracheae sufficing to supply the wood for the 

 branch (see Fig. 58, br, from L. brevifolium). 



To complete the description of the vegetative organs 

 of the Lepidodendreae, we ought now to describe the 

 root. As, however, we cannot as yet distinguish with 

 certainty between the underground organs of Lepido- 

 dendron and those of Sigillaria, it will be necessary to 

 postpone their consideration until the latter genus has 

 also been described. 1 



1 The anatomy of Lepidodendroid stems was dealt with by Williamson 

 in Parts ii. , iii., ix., a., xi., xii. , xvi., and xix. of his series of memoirs in 

 the Philosophical Transactions, 1872-93. Some of his final conclusions 

 are summed up in his last work, " Growth and Development of the 

 Carboniferous Arborescent Lepidodendra" Mem. and Proc. Manchester 

 Lit. and Phil. Soc. ser. iv. vol. ix. 1895. 



