♦ 



c 





1920] 



SIFTON—CYCADS 



435 



Fig. 7. — Dioon spinulosum: radial section of secondary wood of stem, 

 showing pit arrangement and bars of Sanio; X225. 



Fig. 8. — Dioon spinulosum: radial section of secondary wood of stem, show- 

 ing trabeculae ; X 2 2 5 . 



Fig. 9. — Dioon spinulosum: radial section of secondary wood of stem, 

 showing pitting in contact with medullary ray; X445. 



Fig. 10. — Dioon spinulosum: radial section of secondary wood of stem, 

 with fusion pits near end of tracheid; X445. 



Fig. 11. — Dioon spinulosum: radial section of secondary wood of stem, 

 showing pitting in contact with wood parenchyma, and unilateral pits between 

 two tracheids; X445. 



* 



1 



r 



