Surface of area just above base [see diagram, pi. 2, no. 4], showing 

 greatly dilated cortex, seamed, and marked by very distant and 

 oblique though irregular rows of leaf cushions (P), the indi- 

 vidual cushions being very close, serially, in each row. The 

 irregularly rhomboidal depressions between the leaf cushion rows 

 are characteristic of the lower part of old trunks of Sigillaria 

 and Lepidodendron. 



