318 



The fungus which occured on Psilophyton is identical 

 with Palaeomyces agglomerans, described by Kidston 

 and Lang (1921, V, p. 862. fig. 39—41); it occurred not 

 only in the tissues of Rhynia major, but also in the matrix 

 and on the outer surface of the plants. 



The structure of the outer walls of the epidermis in 



Fig. 4. Rhynia major Kdst. and L. Transverse section of 

 the outer wall of the epidermal cells. 



Rhynia was very seldom preserved ; in Gome thin sections ^) 

 however I could see some détails. On the outer side of 

 the epidermis there is a cuticle of only a few /^. thick. Its 

 substance is clearly defîned from the rest of the prépara- 

 tion by its brighter yellow colour. In many cases only this 

 cuticle is shown ; in other places however there is a similar 

 layer, having the same colour and structure on the inner 

 side of the wall, doubtless of the same nature. Between 

 this layer there is some pigment, which is continuons in 

 the radial walls between the epidermal cells. Thèse facts 

 lead to the supposition that in a number of cells cutine 

 layers are disposed on the inner side of the primary cell- 

 wall only to the surface of the leaf; in transverse section 



') E.g. in section B 34 of the Palaeobotanical collection of the Botanical 

 Laboratory, Groningen. 



