PLATE 5. CORDAITES BRANDLINGII. Radial section immediately external to 

 fig. 4, showing the complete formation of scalariform structure, x 153.4 



PLATE 6. CORDAITES BRANDLINGII. Radial section immediately external to 

 fig. 5, showing the reduction of the scalariform structure into imperfectly 

 formed, multiseriate, bordered pits, x 153.4 



