PLATE XL. 



FeNESTELLA (PoLYPORA) QUADRANGUIiARIS. 



Page 158. 

 See Plates 35 and 36. 

 F\g. 1. A lateral view of a branch. (X 6) 



Fig. 2. A portion of the non-celliiliferous face of a fronrt. distinctly showing the carinse of the branches 

 and di.s.sepiments, and the nodes opposite the di.ssepimenta. (X 6.) 

 Upper Helderberg gi-oup. Falls of the Ohio river. 



Fenestella (Polypora) sdbmutans. 

 PiigB is;. 

 Fig. 3. A portion of the non-celluliferous face of a frond, natural size. 

 Fig. 4. A poi-tion of the preceding, showing comparatively regular branches, with dissepiments nearly 



equal in width to the branches. (X 6.) 

 Fig. 5. Another pai-t of the same, showing more irregular branches and proportionally narrower dissepi- 

 ments. (X 6.) 



Upper Helderberg group. FWls of the Ohio river. 



Fenestella (Polypora) aculeata. 



Page IS7. 

 See Plate 35. ' 



Pig. 6. A portion of the non-celluliferous face of a frond, natural size. 

 Fig. 7. An enlargement of a portion of the non-celluliferou.<< face. (X 6.) 



Fig. 8. An enlarnement from another fi-ond. having stronger branches, widei- dissepiments, and more 

 numerous and prominent nodes. The fenestrules over a portion of the specimen are also more 

 broadly oval. (X B.) 

 Fig. 9. Transverse section of the branches of fig. 10, showing their form and the interior space occupied 



by the cells. (X 6.) 

 Fig. 10. A portion of the cellulifei-ous face of a frond, showing the carinate branches and dissepiments, 



with nodes on the cariiiie of the bi-ani^hea. (X S.) 

 Fig. 11. A latei-ftl view of one of the branches of fig. 10, showing the node-like spines on both the cellu- 

 liferous and non-cellnlifenms faces. (X 6.) 



Upper Helderberg group. FalU of the Ohio river. 



Fenestella (Polypora) brevisulcata. 



Page 168. 

 Fig. 12. The non-celluliferous face of a frond, natural size. 



Figs. 13, 14, 1.^. Enlargements of <iifferent portions of fig. 12, showing the comparative size and character 

 of the branches and dissepiments. (X 6.) 



Upi)er Helderberg group. WalpoU, Ontario, Canada. H^Uj 



Fenestella (Polypora) striatopora. 



Page 168. 

 Fig. If). Transverse section of the branches of fig. 17, showing their form and the space occupied by the 



cells. (X 6.) 

 Fig. 17. An enlargement of a portion of the non-celluliferous face of a frond, showing the comparative 



size and character of the branches and dissepiments. (X t5.) 

 Fig. 18. An enlargement of a poi-tion of the cellulifei-ous face of a frond whei-e the elevated margins of 



one siile of the cell a|>ertures are very strongly developed. (X 6.) 

 Fig. 19. An enlargement from another portion of the same frond, showing the margins of the cell 



apertures more equally developed. (X ti.) 



Upper Helderberg group. Falls of the Ohio river. 



