680 ON OLD RED SANDSTONE PLANTS FROM THE RHYNIE CHERT BED. 
Fig. 103. Another portion showing sporangia filled with spores (s. s .) in the neighbourhood of one of the 
peculiar axes with two steles, x 30. (No. 2508.) . 
Fig. 104. Another portion showing a large stem of Asteroxylon (a), two cylindrical strands of xylem ( b ) 
composed of Asteroxylon tracheides, fragments of xylem of Asteroxylon ( c ), and a peculiar axis with its 
cylindrical strand of xylem (d). x 105. (No. 2509.) 
Fig. 105. Another portion showing a rhizome-like structure which is cut transversely and is giving off a 
small lateral branch, embedded in the peat formed of characteristic specimens of the peculiar axes, x 33. 
(No. 2509.) 
Fig- 106. Another portion showing a rhizome-like axis of Asteroxylon at a, and at b one of the peculiar 
axes with the cortex preserved. These are embedded in a peat formed of fragments of Asteroxylon. x 33. 
(No. 2510.) 
Plate XYI. 
Fig. 107. Transverse section of one of the small peculiar axes, ep., epidermis; c., cortex; ph., phloem; 
x. x., two strands of xylem. x 33. (No. 2511.) 
Figs. 108-113. Steles of the peculiar axis in transverse section showing different distribution of the xylem 
and phloem. Description in the text (p. 660). x 60. (Fig. 108, No. 2508; Fig. 109, No. 2507; Fig. 
110, No. 2505; Fig. Ill, No. 2507; Fig. 112, 2509; Fig. 113, No. 2507.) 
Fig. 114. Stele of peculiar axis showing horse-shoe shaped xylem {as.) and its relation to the phloem 
(ph.). x 60. (No. 2512.) 
Figs. 115, 116. Specimens of the peculiar axis with two distinct steles enclosed in the one epidermis. 
The cortex, as usual, has decayed. x 60. (Fig. 115, No. 2505 ; Fig. 116, No. 2506.) 
Fig. 117. Specimen of the peculiar axis with small traces departing from the stele. x 33.' (No. 2507,) 
Fig. 118. Portion of the peculiar axis with the cortical tissues preserved shown in fig. 106. ep., epidermis ; 
c., cortex; x., xylem. x 105. (No. 2510.) 
Plate XYII. 
Fig. 119. Transverse section of a specimen of the peculiar axis the xylem of which consists of larger 
tracheides than usual and is giving off traces radially, x 60. (No. 2506.) 
Fig. 120. Specimens of the peculiar axis the steles of which are giving off smaller portions laterally. 
There are fragments of the sporangial walls in the adjacent matrix. x 60. (No. 2509.) 
Fig. 121. Stoma in surface view from the epidermis of one of the peculiar axes. x 160. (No. 2505.) 
Fig. 122. Xylem of one of the peculiar axes in longitudinal section showing the narrow tracheides without 
recognisable thickening, x 105. (No. 2512.) 
Fig. 123. Longitudinal section of a sporangium filled with spores. X, the place of dehiscence in the 
thickened epidermis. x 50. (No. 2513.) 
Fig. 124. Another sporangium in longitudinal section, only the epidermal layer persisting. X, place of 
dehiscence, x 33. (No. 2508.) 
Fig. 125. Overlapping portions ( a and b) of the epidermal layer from the region of dehiscence of a crushed 
sporangium, x 105. (No. 2508.) 
Fig. 126. Portion of the peat including at s a sporangium cut longitudinally, a, peculiar axis giying off 
branches as in fig. 120 ; b, strand of Asteroxylon tracheides. x 33. (No. 2506.) 
Fig. 127. Spores from the sporangium in fig. 123. x 160. (No. 2513.) 
We have again to gratefully acknowledge our indebtedness to the Executive Committee of the Carnegie 
Trust for a grant to defray the cost of the plates illustrating this memoir. 
