376 



BENNETTITALES 



[CH. 



has more compact wood than that of recent Gycads ; the medullary 

 rays are 1 — 2 cells broad except near the perimeduUary region 

 where they are broader and the individual cells are tangentially 

 stretched (fig. 508, B). The tracheids are scalariform, but in 

 C. micromyela, an exceptional type, some of the xylem-elements 

 have 1 — 2 rows of separate bordered pits (fig. 538). The phloem 



s. s ss. 



Fig. 509. Cycadsoidea Wielandi. Tangential section of secondary xylem of 

 the stem. (After Wieland; x 100.) 



(fig. 518, B) is characterised by 'an alternation of thick- walled 

 elements and thiimer cells^. From the main stele branches are 

 given ofi to supply the flowering shoots in the form of a cyhndrical 

 stele Uke that of the primary axis, and each leaf-trace arises as a 

 single bundle which, in the form of a U-shaped strand (fig. 519, A), 



1 Wieland (06) p. 76; Capellini and Solms-Laubaoh (92) PI. v. fig. 6. 



