PLATE XXXV. 



Fbnestella (Polypora) oelsipora, var. minima. 



Pnge 151. 

 See Plate 41. 



Fig. 1. The base and lower portion of a frond, natural size. 



Fig. 3. A portion of the non-celluliferous face of a frond. (X 6.) 



Fig. 3. A portion of the celluliferous face of a fi-ond, enlarged, showing the fenestrules narrower than on 

 the non-ceHidiferous side, and the foi-m and arrangement of the cell apertui-es. (X 6.) 



Fig. 4. A portion of one of the branches of fig. 3, enlarged, showing the form of cell apertures and mar- 

 ginal ra<liating lines, which are proliably caused by weathering. (X 18.) 

 Upper Helderberg group. Fhlls of the Ohio river. 



Fbnestella (Polypora) aculeata. 



Page 157. 

 See Plate 40. 

 Kg. S. A specimen, natural size, showing the spreading striated base and lower poi'tion of the frond. 

 Pig. 6. An enlargement of the non-celluliferous face of the preceding, showing the form and nodose 



character of the branches. 

 Fig. 7. An enlargement of the celluliferous face of the same, showing the comparative size of the 

 branches and dissepiments, the form and arrangement of cell apertures and the numerous 

 spinules. 



Upper Helderberg group. Falls of the Ohio river. 



Fenestella (Polypora) quadrangulabis. 



Page 168. 

 See Plates 36 and 40. 

 Fig. 8. The non-celluliferous face of a specimen, natui'al size. 

 Fig. 9. A portion of the celluliferous face of the preceding, enlarged, showing the comparative size of 



bi-anches and fenestniles, the form and arrangement of cell apertures. (X 6.) 

 Fig. 10. A portion of the non-celluliferous .lide of the same, enlarged, showing comparative size of the 



branches and dissepiments, the carination of the branches and the less distinct carination of 



the dis-sepiments. 

 Fig. 11. An enlargement of one side of a branch, to show the form of the spines of the non-celluliferous 



face of the branches. 

 Fig. 12. A specimen, natural size, showing the base and lower portion of the frond, with numerous 



processes attached to, and growing upon a frond of FeneMella ( Unitrypa) stipata. 

 Fig. 13. A portion of the celluliferous face of fig. 12, enlarged, showing the form and arrangement of the 



cell apertures and the prominent, irregular nodes. (X •>•) 

 Upper Helderberg group. Fallji of the Ohio river. 



Fenestella (Polypora) l^evistriata, n. sp. 



Page 159. 

 Kg. 14. A portion of the non-celluliferous face of a frond, natural size. 

 Fig. 15. An enlargement of a portion of the non-celluliferous side of fig. 14, showing the comparative 



size of the branches and dissepiments, and the angular and spinulose branches. 

 Fig. 16. An enlargement of a portion of the celluliferous face of fig. 14, showing the character of branches 

 and dissepiments and the form and an-angement of the cell apertures. 

 Upper Helderberg group. Falls of the Ohio river. 



Fenestella, sp. indet. 



Fig. 17. A specimen, showing the bases of several fronds, growing upon an overthrown individual of the 



same or another species. 

 Vig. 18. A specimen, showing the concentric aggregation of the substance as produced daring the process 



of silification. 



Upper Helderberg group. 



