1 84 STUDIES IN FOSSIL BOTANY 



evident that all the upper part of the cone was occupied 

 by microsporangia, and the lower by megasporangia, 

 as in most species of Selaginella at the present day 

 (Fig. 74). Fig. 72 represents a transverse section from 

 the upper, and Fig. 73 one from the lower part of the 

 cone ; the former shows microsporangia, the latter 

 megasporangia only. 



The structure of the sporangium is similar to that of , 



Fig. 73. — Lepidostrobus Veltheimianus. Transverse section of cone, through megaspore- 

 region. sp., sporophylls (only partially shown); sm., megasporangia; ma., the 

 spinose megaspores. X about 7. S. Coll. 413. (G. T. G.) 



the last species ; the wall consists of narrow prismatic 

 cells, sometimes divided by a transverse septum. From 

 the base of the sporangium a radial plate of tissue 

 runs up into the cavity, and often forks into two above. 

 This structure may be compared with the trabeculae of 

 Isoetes. It is best shown in the microsporangia, but 

 evident traces of it are present in the megasporangia 

 also. The microspores occur in immense numbers in 

 their sporangia, and are generally found united tetra- 

 hedrally in fours. They are of small size, not exceeding 



