854 OLD RED SANDSTONE PLANTS FROM RHYNIE CHEBT BED, ABERDEENSHIRE. 
Fig. 22. Stem of Rhi/nia Gwynne-Vaughani in transverse section showing enlargement of the cells in 
certain regions as compared with others where the cells are of normal size, x 22. (No. 2520.) 
Fig. 23. Asteroxylon Macldei. Portion of cuticle of a stem viewed obliquely from the surface. The 
longitudinal dark lines on the epidermal cells are shown, x 100. (No. 2479.) 
Plate Y. 
Asteroxylon Macldei. 
Fig. 24. Section of the chert showing a large rhizome bending downwards into the peat and penetrating 
a large stem in the latter; the basal region of the rhizome hears small scale-leaves, x 3|. (No. 2557.) 
Fig. 25. Transverse section of the bud of a leafy shoot, passing just above the apical cone and showing 
the arrangement of the small leaves. x 14. (No. 2554.) 
Fig. 26. Transverse section of the stem from the same series as the preceding figure passing immediately 
below the apex. x 14. (No. 2553.) 
Fig. 27. Portion of the section in fig. 26 more highly magnified, ep., epidermis; o.c., outer cortex ; i.c.o., 
outer zone of inner cortex; i.cm., trabecular middle zone of inner cortex ; i.c.i., inner zone of inner cortex; 
l.t., departing leaf-traces ; x., xylem of the ends of the rays of the stellate xylem. x 35. (No. 2553.) 
Fig. 28. Stele of a section lower in the series showing the poles of the stellate xylem still unconnected 
by central xylem. x 50. (No. 2550.) 
Fig. 29. Transverse section of the stem at the lowest level in the series., x 14. (No. 2547.) 
Fig. 30! The stele of the section shown in Fig. 29. The central xylem is still undifferentiated except for 
a few tracheides. x 50. (No. 2547.) 
We again gratefully acknowledge our indebtedness to the Executive Committee of the Carnegie Trust 
for a grant to defray the expense of the plates illustrating this memoir. 
