91 



Fig. 172. Sekujinella nipestris. Fragment of section through mcgaspore mem- 

 brane. X 1000. 



Fig. 173. Selaginella selaginoides. Fragment of section through megaspore 



membrane ( x 2000). An electi'on micrograph showing the fme structure of 



part of the membrane is shown in PI. Ill (facing p. 94), lower figure. 



Fig. 174. Selaginella apus, microspore, a, distal face; b, proximal face (a, h 

 X 1000). Lower left-hand detail: lateral view ( x 250); upper detail: sclerine 



stratification (x 2000). 



7 - 565617 G. Erdtman 



