784 OLD RED SANDSTONE PLANTS FROM RHYNIE CHERT BED, ABERDEENSHIRE. 



Fig. 67. Portion of the wall of the sporangium in fig. 62 more highly magnified. ep., thick-walled 

 epidermis; m.l., decayed middle layers of wall; tap., tapetum ; sp., spores. x 60. (Slide No. 2393.) 



Fig. 68. Transverse section of another sporangium, ep., thick-walled epidermis ; m.l., middle layers of 

 wall; tap., tapetum; sp., spores. x 14. (Slide No. 2395.) 



Fig. 69. Section through the silicified peat passing transversely a sporangium (s.) and an axis which 

 bore another sporangium. The axis is shrivelled and altered, but in a manner characteristic of Rhynia. 

 c, cortex of axis; v.s., vascular strand. x 11. (Slide No. 2421.) 



Plate X. 



Fig. 70. Spores, some still united in tetrads, from the sporangium shown in fig- 68. ^ 160. (Slide 

 No. 2395.) 



Fig. 71. Spores free in the silicified peat, one showing the triradiate marking. x 160. (Slide 

 No. 2395.) 



Fig. 72. Adventitious branch widening out from very narrow base and occurring free in the silicified 

 peat. ° x 33. (Slide No. 2406.) 



Fig. 73. Transverse section of small stem without any stele. x 60. (Slide No. 2391.) 



Fi". 74. Transverse section of stem, the cortical cells of which are of larger size in one sector than 

 elsewhere, x 20. (Slide No. 2392.) 



Fie. 75. Transverse section of large stem showing commencing decay of the inner and persistence of the 

 outer cortex, x 20. (Slide No. 2387.) 



Fig! 76. Transverse section of a partially decayed stem, ox., remains of outer cortex ; ph., phloem ; 

 x. xylem. The space marked i.e. was originally occupied by inner cortex. x 60. (Slide No. 2393.) 



Fi". 77. Transverse section of a similar stem to that in fig. 76, but with the inner portion of the phloem 

 broken down. Lettering as in fig. 76. x 60. (Slide No. 2393.) 



Fi». 78. Longitudinal section of the stele of a partially decayed stem ; the xylem (x.) has lost its 

 thickenings, while the phloem (ph.) has assumed a dark colour. x 60. (Slide No. 2395.) 



(All the figured specimens are in the collection of Dr R. Kidston.) 



