1865.] DAWSON COAL-FORMATION. 167 



Fig. 11. The same : longitudinal section, magnified 90 diameters : a, one of the 

 concentric rings of compact coaly matter. 



12. The same : portion of a cell showing areolation, natural size. 



13. The same : transverse section, natural size : a, pith ; b, wood, composed 



of" alternate circles of areolated cells and compact coaly matter ; c, 

 coaly bark. 



Plate VI. 

 Fig. 14. Araucarites gracilis : branch with leaves, three-fourths the natural size. 

 1.5. Sigillaria Brownii: portion of two ribs, 4 feet above the level, one-half 

 the natural size : a, cortical ; h, decorticated. 



16. The same : portion of one rib near the root, furrowed and with vascular 



scars widely separated. 



17. The same : trunk 1 foot in diameter at the base, showing the origin of 



the ribs. 



18. The same : photograph of a portion of the upper part of the stem, 



one-half the natural size. 



19. The same : portion of the base of the stem, one-half the natural size, 



from a photograph. 



20. The same : Sigillarian root of this or an allied species. 



21. Sigillaria planicosta, from a photograph, one-half the natural size; 



21 a, scar and part of rib, one-half the natural size. 



22. catenoides, from a photograph, one-half the natural size ; 22 a, scar 



and part of ribs, one-half the natu.ral size. 



23. striata : flattened stem, from a photograph, two-thirds the natural 



size; 23 a, part of stem, same size; 23^, scar, enlarged. 



24. eminens : decorticated stem, from a photograph, much reduced ; 



24 a, scar, one-half the natural size. 



25. scutellata, from a photograph, two-thirds the natural size, with band 



of interrupted growth; 25 «, ordinary ai-eole, natural size; 25 6, are- 

 oles from the regular band, natural size. 



Plate VII. 

 Fig. 26. Sigillaria elegans : decorticated stem, from a photograph, one-half the 

 natural size, with band of interrupted growth at /3 ; 26 a, corticated 

 and flattened stem, one-half the natural size, with branches at /3 & y ; 

 26 h, leaf of S. elegans ; 26 c, areoles of a branch ; 26 d, areole of 

 main stem. 



27. Bretonensis: corticated stem, from a photograph, two-thirds the 



natural size ; 27 a, areole, natural size. 



28. Sydnensis: decorticated stem, from a photograph, two-thirds the 



natural size ; 28 a, areoles of decorticated stem ; 28 5 & c, variety of 

 Stigmarian root attached to this species. 



29. AnthoUthes squamosus, from a photograph, two-thirds the natural size. 



30. Ehabdocarpi, from a photograph, two-thirds the natural size ; 30 a, 



a larger specimen of ihe same ; 30 b, single nutlet of the same, 

 natural size. 



30 c. pygmcBus : fragment, natural size. 



31. Calamodendron approximatum, one-half the natural size ; 31 a, cast of 



pith ; 31 b, coaly or woody investment ; 31 c, tissues of wood of 

 Calamodendron, magnified. 



31 d. Tissues of a different species of Calamodendron or of Calamites. 



Plate VIII. 

 Fig. 32. Leaflets of Cyclopteris Acadica, from a photograph, one-third the na- 

 tural size ; 32 a, petiole of the same, one-third natural size ; 32 b, 

 divisions of petiole, one-half the natural size ; 32 c, leaflets ; 32 d, 

 leaflet ; 32 e, leaflet enlarged, showing venation ; 32 /, striation of 

 petiole enlarged ; 32 g, h, remains of fructification ; 32 i, base of pe- 

 tiole, much reduced. 

 33. Megaphyton humile : (i, leaf- scars ; y, part of axis : from a photograph, 

 two-thirds the natural size. 



n2 



