io6 



STUDIES IN FOSSIL BOTANY 



towards the axis, the epidermal cells are much enlarged, 

 and these large cells of the pedicel are continuous with 

 those that form the wall of the sporangium itself 



(Figs. 43 and 44). To- 

 wards the free end of 

 the sporangium, the cells 

 of the wall become much 

 smaller, and it was prob- 

 ably at this end that 

 dehiscence took place, 

 the large cells perhaps 

 performing the functions 

 of an annulus. These 

 cells were strengthened 

 by buttresses projecting 

 from their lateral cell- 

 walls, much as in the 

 sporangium of Cala- 

 mostachys. The spor- 

 angium is seated, with 

 a broad base, on the 

 recurved end of the 

 pedicel ; the sporangial 



Fig. 44. — Spheiiophyllum Damsom. Sporangio- *■ ° 



phore and its sporangium, shown in trans- wall in this region is 

 verse section above, and in longitudinal 



section (somewhat oblique) below, sp, spor- lined by a delicate tissue 



angiophore ; sm, sporangium, containing y-i-.- \ 



spores. X 45. Phil. Trans., W. and S. \P X %- 44> 



Will. Coll. .8,8, H. and E. The spQres wer£ 



numerous in each sporangium; and so far as at present 

 observed, were all of one kind, though rather variable 

 in size. Their average diameter is about .09 mm. 

 The spore-membrane shows a characteristic sculpturing, 

 consisting essentially of prominent spines, connected 



