734 ME W. T. GORDON ON 



(12) StbnzbLj G., " Die G-attung Tubicaulis Cotta," Mitth. aus clem Kyi. min. yen/. Museum in Dresden, 

 Heft 8, 1889. 



(13) Stopes, Miss M. C, "A New Fern from the Coal Measures: Tubicaulis Sutcliffii, sp. now," Mevi. 

 and Proc. Manchester Lit. and Phil. Sue, vol. 1., pt. iii., 1906. 



(14) Tansley, A. G., "Lectures on the Evolution of the Filicinean Vascular System," New Phytoloyid, 

 1907. 



(15) Williamson, W. C, "On the Organisation of the Fossil Plants of the Coal Measures," Phil. Trans_ 

 Hoy. Soc, 1874. 



EXPLANATION OF PLATES. 



(Figures are all from untouched negatives.) 



Plate I. 



Diplolabis rimieri. 



Fig. 1. Transverse section of stem-xyleni. x. = outer xylem ; x} = inner xylem. x 12. (Slide 742.) 

 Fig. 2. Transverse section of stem near a dichotomy, x. = outer xylem; x. 1 = inner xylem. x 12. 

 (Slide 735.) 



Fig. 3. Section following that of fig. 2. x. = outer xylem; x} = inner xylem. x 12. (Slide 736.) 

 Fig. 4. Section following fig. 3. x. — outer xylem ; .r. 1 = inner xylem ; rl. tr. = root-trace (compare relative 

 size of root and stem). x 10. (Slide 737.) 



Fig. 5. Longitudinal section of stem-xylem. x. = outer xylem; x. 1 = inner xylem. x 10. (Slide 806.) 

 Fig. 6. Longitudinal section of outer xylem showing reticidate fitting of tracheides. x 30 (Slide 806.) 

 Fig. 7. Longitudinal section of inner tracheides, showing the short tracheides with reticulate thickenings. 

 x 48. (Slide 807.) 



Fig. 8. Longitudinal section of protoxylem elements with scalariform thickenings. x 130. (Slide 338.) 

 Fig. 9. Oblique transverse section of stem-xylem near a dichotomy. One arm of the branch is cut trans- 

 versely (st.„), the other is cut obliquely (st.^). A petiole and a root are also shown passing out. st^ st. 2 = the 

 two branches of the dichotomy; pet. tr. = petiole-trace ; rt.tr. = root-trace; o. c. = outer cortex, x 3*2. (Slide 338.) 

 Fig. 10. Section following that shown in fig. 9. sf. = stem-xylem ; pet. tr. = petiole-trace ; rt. tr.= root- 

 trace ; o. c. = outer cortex; z. = root-trace lying outside the stem-cortex ; z. 1 = petiole-trace external to outer 

 cortex, x 3"2. (Slide 337.) 



Fig. 11. Section after fig. 10. Lettering similar to that of fig. 10. rt. tr. = root-trace of fig. 10 after the 

 xylem has become detached from that of the stem ; rt. tr. 1 = root-trace, leaving the stem at a higher level than 

 the former. x 3"2. (Slide 336.) 



Fig. 12. Specimen of petiole with pinna? departing from it. Elevation, pet. = petiole ; pin. = pinna. x£. 

 Fig. 13. Same specimen as fig. 12. Plan. pet. = petiole ; pin. = pinna. x ^. 



Fig. 14. Transverse section of stem showing an early stage of petiole departure, x. = outer xylem; 

 x. 1 = inner xylem; prx., prx. = petiolar protoxylems. x 10. (Slide 771.) 



Fig. 15. Transverse section of stem following that of fig. 14. x. = outer xylem; x. 1 = inner xylem : prx.. 

 prx. = petiolar protoxylems. x 10. (Slide 772.) 



Plate II. 

 Diplolabis rbmeri. 

 Fig. 16. Transverse section of stem and petiole following fig. 15. x. = outer xylem ; x. 1 — inner xylem ; 

 prx., prx. = protoxylem. x 10. (Slide 773.) 



Fig. 17. Transverse section above fig. 16. x. = outer xylem ; x. 1 = inner xylem ; prx., prx. = protoxylem. 

 x 10. (Slide 775.) 



Fig. 18. Petiolar departure, later stage than fig. 17. Petiole-trace distinct. *. = outer xylem ; x. 1 = inner 

 xylem ; prx., prx. = protoxylem. x 1L6. (Slide 740.) 



Fig. 19. Petiolar departure, stage beyond fig. 18. x., a:., 1 a.\\A prx. as before. x ll - 6. (Slide 741.) 



