PLATE XLIII. 

 Fenestella (Polypora) robusta. 



Page 158. 

 S«e Plates 84, 37. 39 and 46. 

 Fiff . 1 . An enlargement of a jidrtion of the celluliferous face, showing the rows of cell apertui-es separated 

 by narrow riilg-es. (X 6.) 



Upper Helderberg group. Walpole, Oittario, Canada. 



Fenestella (Ptiloporina) conica. 



Page 172. 

 Fig. 2. A nearly entire frond, natui-al size. 



Figs. 3, 4. Enlargements fi oni the preceding, showing the pnmary and secondary branches. 

 Upper Helderberg gi-oup. Scholiarie, N. T. 



Fenestella (Ptiloporina) pinnata. 



Page 172. 

 Fig. 5. A portion of a frond, natural size. 



Fig. 6. An enlargement fiiim the preceding, showing the striated branches snd dissepiments. 

 Upper Helderlierg grouj). Schnharie, N. Y. 



Fenestella (Ptiloporina) di.sparilis. 



Page 173. 

 Pig. 7. An enlargement of the non-cellnliferons face of a frond. (X 6.) 



Fig. 8. An enlargement from a decorticated specimen, showing the aiTangement of the cells on the 

 interior of the branches. (X 6.) 



Upper Helderberg group. Walpole, Ontario, Canada. 



Fenestella (Ptiloporina) sinistralis. 



Page 174. 

 Fig. 9. The non-celluliferoua face of a large portion of a frond, natural size, showing the disposition of 

 the primary and secondary brancnes. 



Schohane grit. Schoharie, N. Y. 

 I 



Fenestella (Polypora) rustica. 



Page 169. 

 Fig. 10. A portion of the non-celluliferous face of a frond, natural size. 

 Fig. 11. An enlargement fi-om the pi-eceding. (X 6.) 



Fig. 12. An enlargement of the celluliferous face, showing a weathered coniiition of the specimen. (X 6.) 

 Fig. 13. An enlargement showing the charactera of the celhiliforous face of the frond. (X (i.) 

 Upper Helderberg group. Walpole, Ontario, Ca7iada. 



