1862.] DAWSON DEVONIAN PLANTS. 329 



conditions in these two periods ; but the facts are not yet sufficiently 

 numerous to prove this. 



7. The above general conclusions are not materially different from 

 those arrived at by Gceppert, Unger, and Bronn, from a considera- 

 tion of the Devonian Plora of Europe. 



EXPLANATION OF PLATES XIL— XVIL 



Illustrative of the Devonian Flora of North-eastern America. 



Plate XIL 



Fig. L SyringoxylonmirahiU', longitudinal section, highly magnified, a, 

 woody fibres ; h, medullary rays ; c, ducts. 



2. ; transverse section. 



3. ; portion of a duct, highly magnified, showing the pores. 



4. ; medullary ray, highly magnified. 



5. ; transverse section, highly magnified ; letters of reference as in 



fig.l. 



6. Acanthophyton spinosum : a, smooth species or variety ; b, punctated 



species or variety. 



7. Sigillaria Vanuxemii : a, retaining the outside ; b, decorticated ; c, axis. 



8. Leptophlceum rhombicum : a, natural size ; b, an areole enlarged. 



9. Cyclopteris Brownii. 



10. Lepidodendron corrugatum : a, portion of a small stem ; b, part of a 

 larger stem. 



Plate XIII. 



Fig. 11. Dadoxylon Halli; longitudinal section, magnified. 



12. Sigillaria Palpebra : a, natural size ; b, an areole magnified. 



13. Stigmaria exigua. 



14. Syringodendron gracile : a, natural size ; b, an areole magnified. 



15. Didymophyllum reniforme: a, natural size; b, an areole magnified. 



16. Asterophyllites acicularis : a, natural size ; b, a leaf enlarged. 

 17- A. latifolia : a and c, natural size ; b, leaf enlarged. 



18. A. scutigera ; ordinary aspect of the stem. 19. Apex of stem. 20. Stem 

 compressed diagonally. 



21. Annular ia acuminata. 



22. Finnularia dispalans. 



23 & 24. Cardiocarpum cornutum. 

 25. C. acutum. 



Plate XIV. 



Fig. 26, 27, 28. Lepidodendron Gaspianum, in various states. 

 29 & 30. Psilophyton elegans : a, fructification. 



31. Cordaites Robbii: a, a group of young leaves; b, pointof leaf ; c, base 



of leaf ; d, venation magnified. 



32. Rhachiopteris tenuistriata : a, natural size ; b, a portion magnified. 



Plate XV. 



Fig. 33. Cyclopteris obtusa. 



34. C. varia. 



35. Neuropteris serrulata : a, natural size ; b, a pinnule enlarged. 



36. N. polymorpha : ato g, various forms of pinnules. 



37. Hymenophyllites Gersdorffii : a, natural size ; b, magnified. 



38. Sphenopteris marginata : a, natural size ; b, magnified. 



39. Hymenophyllites obtusilobus ; natural size. 



40. Fecopteris decurrens : a, a portion of a frond ; b, terminal leaflet {c, 



magnified). 



41. P. ingens: a, natural size: b, magnified. 



