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they are separated from each other by the radial walls of 

 the epidermal cells and from the outer cuticle by the primary 

 cellwall. The pigment which occurs in the thin sections 

 is a remainder of the latter. 



When an epidermis is altered during fossilisation, the 

 cuticular substance because of its différent chemical com- 

 position was more résistent to decay, and after treatment 

 with Eau de Javelle the radial walls of the epidermal cells 

 wholly disappeared, thus leaving a furrow in the cuticular 

 substance which is seen as a line in the dark-coloured 

 bands, which mark the boundary between the epidermal 

 cells, In this way the somewhat peculiar structure of the 

 cuticle in Psilophyton might be explained in accordance 

 to the structure of the cuticle of Rhynia. 



Thus the resemblance between Psilophyton and Rhynia 

 is not only in their gênerai habit and in the position of 

 the sporangia, but also the structure of the cuticle shows 

 similar features and on both plants the same fungus lived. 

 The présence of a well developped cuticle and cuticular 

 layers combined with the habit and the présence of rudimen- 

 tary stomata suggest a xerophytic habit. The supposition 

 that thèse plants were sea-plants seems no longer tenable. 



