XVIl] 



STIGMARIA 



241 



which centripetal primary wood is well developed between the 

 secondary xylem and the centre of the stele. The Stigmarian 

 axis of Bothrodendron was originally figured by Williamson 

 as Lepidodendron mundum^. The chief difference between 



Fig. 210. Stigmaria. 



A. Transverse section of vascular bundle of rootlet and part of outer 

 cortex, t, tracheae. (After F. E. Weiss.) 



B, 0. Vascular bundle of rootlet ; in C a series of small tracheae are 



shown extending from the protoxylem. 



D. Rootlets from the outer cortex of E. 



E. Part of a large Stigmaria : St, stele ; s, intruded rootlet. 



F. Vascular bundle and tracheae passing obliquely towards the 

 outer cortex, c^. 



G. Outer cortex of Stigmaria. 



H. Diagrammatic section of Stigmaria : p, phelloderm ; r, rootlets. 



Weiss's specimen and those described by Renault^ as the 

 Stigmarian axes of Sigillaria Brardi, is that in the English plant 

 the centripetal wood forms a cylinder of uniform breadth 



Williamson (89) A. 



2 Renault (96) A. 



