Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/287

DAWSON—SIGILLARIA, CALAMITES, AND CALAMODENDRON. 161 Fig. 9. Sternbergia, pith of the same, natural size; 9 a, discigerous tissue of the same.

10. Another stem, probably Coniferous, with Sternbergia pith. 11. Woody tissue of prostrate Sigillaria; 11 a, bast-tissue of the same. 12. Woody tissue of a Sigillaria; 12 a, medullary ray. 13. Tissue of a Sternbergia similar to fig. 9. 14. 15, 16. Discigerous tissue of erect trees (Sigillarioe) in mineral charcoal.

Plate IX.

Fig. 17. Calamodendron approximatum, cast of pith; 17 a, 17 b, discigerous and scalariform tissue of the same.

18. Calamodendron invested with woody tissue: A, pith; B, woody cylinder; 18 a, cross section; 18 b, cross section, magnified, showing compression of the tissue; 18 c, discigerous and pseudo-scalariform tissue of the same.

19. Portion of a multiporous vessel of a true Calamites, magnified to the same scale with figs. 17 a & 17 b. 20. Stem of erect Calamodendron (S. Joggins, Nova Scotia), showing its external surface, one-third nat. size.

21. Base of stem of Calamites (S. Joggins), showing rhizoma, reduced.

22. Node of Calamites, showing scars of verticillate branchlets and of radial processes.

Plate X.

Fig. 23. Radial section of stem of Sigillaria of the type of S. Brownii, Dawson, restored, natural size : a, pith ; b, woody cylinder ; c, cellular inner bark ; d, fibrous bark ; e, outer cortical layer.

24. Radial section of the woody cylinder, magnified (letters as above) ; and portions of the tissues more highly magnified below : b 1, inner pseudo- scalariform cylinder ; b 2, 3, 4, discigerous outer cylinder.

25. Radial section, more highly magnified, showing one of the radiating bundles of vessels (this section has been inverted) ; 25 a, single pseudo- scalariform vessel from radiating bundle. 26. Tangential section of the same stem, showing the woody fibres and one of the radial bundles, and the medullary rays.

27. Tangential section showing woody fibres and medullary rays, more highly magnified.

28. Radial arrangement of woody fibres, magnified.

29. Fibres or elongated cells of the bark (d).

Note.—All the drawings of separate fibres and vessels in the above figures are on one scale. VOL. XXVII. PART I. M