12 



GYMNOSPERMS 



agree in making Lyginoptcris a climbing plant. It is certain that the 

 stem was so long and slender and bore such large leaves that the 

 plant could not have stood erect, like the familiar tree-ferns. 



The stems, pieces of which are common in European and American 

 coal balls, range from 2 mm. to 4 cm. in diameter. A transverse sec- 

 tion shows a mesarch siphonostele, with a rather large pith, an 

 abundant development of secondary wood, and a thick cortex dif- 



Fig. 6. — A diagram giving the names of most of the features of the reconstruction 



CARBONIFIiROUS SWAMP FoREST GrOUP 



Lycopodialcs: i. Lcpidodcndron clupcatum Lesq.; 2. Lepidodendron obovatum Sternberg; 3. Lcpido- 

 dendron modulatum Lesq.; 4. Lepidostrobus ovatitolius Lcsq.; 5. Sigillaria rugosa Brogniart; 6. Sigillaria 

 saulli Brogniart; 7. Sigillaria scutcllata Brogniart; 8. Sigillaria lacoci Lcsquereux; 9. Sigillaria laevigata 

 Brogniart; 10. Sigillaria trunk; 11. Stigmaria Ficoides Sternberg; 12. Lepidophloios laricinus Sternberg; 

 13. Selaginellites sp. — Cycadofilicales: 14. Neuropterisheterophylla Brog.; 15. NeuropterisdecipicnsLcsq. 

 (Medullosa stem, Cyclopteris leaves, Trigonocarpus seeds); 16. Lyginopteris oldhamia Williamson 

 (Neuropteris hocnighausi leaves i6a, Lagenostoma ovoides seeds 16b). — Pleridophytts: 17. Cauloptcris 

 gilTordi Lcsquereux Psaronius stem; Pecopteris leaves 17a); 18. Megaphyton frondosum Artis (Psaronius 

 distichus stem); 19. Marioptcris muricata (Schloth) Zciller; 20. Sphcnophyllum emarginatum (Brog.) 

 Kcinig; 21. Calamitcs Annularia stellata (Schloth) Wood. — Gymnosperms: 22. Cordaites borassifolius 

 (Stcrnb.) Ungcr. — Insects: 23. Stenodiclya lobata Brogniart; 24. Mcganeura monyi Brogniart; 25. Gera- 

 rusdonielsi Handlirsch; 26. Arrhcoblaltina bccchcri Sellards.— IVr/efrrdtej- 27. Diplovertcbron punctatum 

 Frilsch; 28. Ccraterpcton galvani Huxley; 29. Eogyrinus attheyi (in background). 



ferentiated into two distinct regions. Leaf traces are conspicuous 

 (figs. 7 and 8). 



The leaf traces are distinctly mesarch, with most of the wood cen- 

 tripetal. In the stele, the leaf traces are single, but the protoxylem 

 soon branches and the trace becomes double, often before leaving 

 the stele. 



The trachcids of the ])rotoxylem have sjiiral markings; the centrif- 



