PLATE XXXVII. 
Fenestella (Polypora) robusta. 
Page 156. 
See Plates 34, 39 and 46. 
Fig-. 1. An enlargement of the non-celluliferous face, showing decidedly angular and carinated branches 
and dissepiments. (X 6.) 
Upper Helderberg group. Walpole, Ontario, Canada. 
Fenestelea (Polypora) distans. 
Page 161. 
See Plate 44. 
An enlargement of a portion of fig. 3, showing more distinctly the form of the branches, the 
prominent distant nodes and fine indistinct striations. (X 6.) 
The non-celluliferous face of a frond, showing the size of branches and dissepiments, and mode of 
growth. 
An enlargement of the non-celluliferous face of another specimen ; as compared with fig. 2, the 
branches are more slender and destitute of nodes, and the striations are stronger. (X 6.) 
A portion of the celluliferous face of a specimen, enlarged, showing the form and arrangement uf 
the cell apertures and the intermediate interrupted striae. (X 6.) 
The non-celluliferous side of a specimen, natural size. 
A portion of fig. 6, enlarged, showing- more distinctly the character of the branches and dissepi¬ 
ments, and the fine indistinct striation of the branches. (X 6.) 
An enlargement of a portion of the celluliferous face of another specimen, showing the form and 
arrangement of the cell apertures and the indistinct intermediate striae ; the elevated margins 
of the cell apertures are obliterated by weathering or maceration. (X 6.) 
The celluliferous face of another specimen, natural size. 
An enlargement of a portion of fig. 9 ; the specimen is much more macerated than that repre¬ 
sented by fig. 8, the branches flatter and the cell apertures open obliquely ; the dissepiments 
are channeled. 
A specimen, natural size, showing the arrangement of the branches and dissepiments, and their 
manner of growth. 
An enlargement of a portion'of fig. 15, showing more distinctly the character of the branches and 
dissepiments, and their comparative size. (X 6.) 
Upper Helderberg group. Near Buffalo, N- Y. 
Fenestella (Polypora) flabelliformis. 
Page 161. 
Fig. 11. The celluliferous face of a frond, natural size, showing the disposition of branches and dissepi¬ 
ments, and manner of growth. 
Fig. 12. An enlargement of a portion of fig. 11, showing more distinctly the comparative size of the 
branches and dissepiments. The branch on the right is in a perfect condition, and shows the 
form and arrangement of the cell apertures, the comparatively strong ridges separating the 
ranges of apertures, and the interrupted striations. The surface of the other branch has been 
macerated and removed, showing the polygonal cells below. (X 6.) 
Upper Helderberg group. Onondaga Valley, N. Y. 
Fenestella (Polypora) perangulata. 
Page 162. 
Fig. 13. The non-celluliferous face of a frond, showing the disposition of the branches and dissepiments, 
and mode of growth. 
Fig. 14. An enlargement of a portion of the preceding. (X 6.) The branches should appear more 
angular than is represented in the figures. 
Upper Helderberg group. Western New Yor/c. 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
Fig. 15. 
Fig. 16. 
