Fig. 6 



Psilotimi nudum: a, portion of plant, showing erect habit; b, 

 fertile region; c, t.s. rhizome; d, t.s. aerial shoot. Tmesipteris 

 tannensis: E, portion of plant, showing pendulous habit; f, g, 

 H, fertile appendages, viewed from different directions; i, t.s. 

 aerial shoot; J, t.s. distal region of shoot; k, theoretical inter- 

 pretation of sporangial apparatus of Psilotales ; l, m, abnormal 

 types of sporangial apparatus 



(a, after Bold; b, e, f, g, h, Pritzel; J, Sykes) 



