476 R. RIDSTON AND D. T. GWYNNE-VAUGHAN ON 



stem. The endodermis is seen to curve round into the concavity of the trace, i.scl., band of sclerenchyma 

 lining the concavity. x 30. (Slide 1686.) 



Fig. 26. Osmundites Srhemnitzensis. Transverse section of a leaf-trace still further out. i.scl., as 

 before, x 30. (Slide 1680.) 



Fig. 27. Osmundites Schemnitzensis. Transverse section of the stipular base of the petiole showing 

 sclerotic strands in the stipular wing, scl., sclerotic ring. x 8. (Slide 1682.) 



Plate IV. 



Fig. 28. Osmundites Schevmitzensis. Transverse section of the stele. o.C, outer cortex ; i.C, inner 

 cortex ; l.t. 1 , departing leaf-trace showing the soft tissue in its axil continuous with the pith ; l.t. 2 , departing 

 leaf-trace showing attachment of roots r, r. x 30. (Slide 1685.) 



Fig. 29. Zygopteris (Diplolabis) Romeri. Transverse section of the stele of the stem, o.xy., ring of 

 normal xylem ; c.xy., central xylem of short tracheae. x 18. 



Fig. 30. Zygopteris {Diplolabis) Romeri. Longitudinal section of the stele ; lettering as in fig. 29. 

 x 18. 



Fig. 31. Zygopteris {Diplolabis) Romeri. Longitudinal section of xylem more highly magnified, showing 

 the pitting. x 110. 



(The specimens from which figs. 29-31 are taken were kindly lent to us by Mr W. T. Gordon.) 



