1 86 STUDIES IN FOSSIL BOTANY 



74). The thick membrane of the megaspores was 



> «& §' Q 



Fig. 75.— Spores of Lepidodendreae. A. Spenccrites insignis. Spore, showing wing in 

 surface-view. sj>, cavity of spore ; w, wing. B. Tetrad, in section, showing three 

 out of the four spores, tetrahedrally arranged. sj>, cavity of spore ; w, wing. A and 

 B x about go. C. Lefiidostrobus Velthcimianus. M, a single megaspore, showing 

 the blunt spines ; m } tetrads of microspores, on the same scale, x about 70. After 

 Williamson, Phil. Trans. D. A single megaspore, probably of L. Veitkeimianus, 

 showing spines and lobes of membrane, surface-view. X 15. After Kidston and 

 Bennie. 



prolonged on the outside into a number of stout curved 

 spines (see Figs. 73, 74, and 75, C). Detached mega- 



