3 2 ° 



STUDIES IN FOSSIL BOTANY 



least two layers of cells, of which the inner, more 

 delicate layer has usually perished. The outer wall 



Fig. 119. — Zygoftteris, sp. _ 1. Group of four sporangia, on a common pedicel (a) x 10. 

 i. Two sporangia on pedicel. The uppei shows the annulus (c) in surface -view, with 

 spores exposed aty"; the lower is in section. X 20. 2 bis. Sporangium, cut in plane 

 passing through annulus. 3. Group of sporangia in transverse section. X 20. 

 Lettering common to the figures : a, common peduncle ; b, sporangial wall ; <,-, 

 annulus ; e, tapetum (?) ; f, spores ; in, pedicel of individual sporangium ; n, 

 probable place of dehiscence. All after Renault. 



shows a marked differentiation ; on two opposite sides 

 it consists of small elongated cells, becoming fibrous 



