220 STUDIES IN FOSSIL BOTANY 



the specimens attains a thickness of about 2 cm.) is 

 here perfectly continuous, but otherwise agrees closely 



Fig. go. — Sigillaria spinulosa. Part of transverse section of stem, showing primary (x) 

 and secondary (jr. 2 ) wood. The former consists partly of separate and partly of 

 confluent bundles. X about 9. , 



with that of the former species. The leaf-traces arose, 

 in this case also, at the outside of the primary wood, 



Fig. 91. — Sigillaria spinulosa. Part of wood, more highly magnified, showing separate 

 primary strands (jr) and secondary wood (jr 3 ). X about 18. Figs. 90 and 91 from 

 photographs by Mr. R. Kidston, F.R.S. 



passed through the secondary zone, and then took a 

 nearly vertical course through the inner cortex, which 



