PLATE XLI. 



Fenkstella (Poltpora) adnata. 



Pase 152, 

 Fig. 1. A ]>ortion of the non-celluliferous face of a frond, natural size. 

 Vig. 2. The celliiliferous face of fig. 1 . 



Fig. 3. A portion of the non-cellulifei-ous face of a frond, having very in-egular branches, with the dis- 

 sepiments frequently wider than the branches. (X 6.) 

 Fig. 4. An enlargement from fig. 1, showing regular anastomosing branches with slender distinct carinse 



along the middle. (X 6 ) 

 Pig. 5. A portion of fig. 2, showing the character of the celluliferous face of the frond, the form and 



arrangement of the cell apertures and occa-sionally larger cell apertures. (X 6.) 

 Fig. 6. An enlargement of a portion of the non-celluliferous face of a frond, showing reg^ular angular 



branches without carinae, while the diss<;piments ai*e often carinated. (X 6.) 

 Fig. 7. A lateral view of one of the branches of fig. 1, showing the form of the dissepiments and the small 



spines on the celluliferous face. (X 6.) 

 Fig. 8. A portion of a non-celluliferous face of a frond, having very regular branches and strongly 



carinated dissepiments. (X 6.) 

 Fig. 10. A portion of a macerated fi-ond, showing nearly equal, rounded branches and dissepiments, with 



cii-cular or sub-circular fenestriiles. fX 6.) 



Upper Helderberg group. Fhllg of the Ohio river. 



Fenestella (Polypora) cultellata. 



Page 160. 

 See Plate 3H. 

 Fig. 9. A portion of the celluliferous face of a frond, showing very distinctly the form and arrati'gemeiit 

 of the cell apertures and the sharp, securiform elevations along the middle of the branch. 

 (X 6.) 



Upper Helderberg group. itW* of the Ohio river. 



Fenestella (Polypora) celsipora, var. minima. 



Page 151. 

 See Plate 35. 

 Fig. 11. A portion of the celluliferous face of a fi-ond, showing the cell apertures an-anged in regular 



longitudinal rows, separateil by narrow i:arina>. (X ti.) 

 Fig. 12. The non-celluliferous face of a frond, showing quadrangular fenestrules wider than the branches. 



(X 6.) 

 Fig. 13. A portion of the non-cellnliferous face of another specimen, showing cii-cular fenestrules which 

 are narrower than the branches. (X 6.) 



Upper Helderberg group. I'hllji of the Ohio river. 



Fenestella (Polypora) celsipora, var. minor. 



Page 151. 

 Fig. 14. An enlai-gement of a portion of the non-celluliferous face of a frond, showing the comparative size 



and character of the branches and dissepiments. (X 6.) 

 Fig. 10. A portion of the celluliferous face of a frond. (X 6.) 



Upper Helderberg group. Ontario, Canada. 



