PLATE XLV—Continued 
F EN ESTEI.LA DEPRESS A. 
Page 111. 
Fig-. 16. An enlargement from the non-celiuliferous face of a frond, showing the striated branches and the 
slender dissepiments, which are only about one-third the width of the branches, and very 
much depressed below their plane. (X 6.) 
Fig. 17. A portion of the eelluliferous face of the same specimen, showing the comparative size and char¬ 
acter of the branches and dissepiments, and the form and arrangement of the cell apertures. 
(X 6.) 
Upper Helderberg group. .Falls of the Ohio river. 
Fenestella tenella. 
Page 105. 
A portion of'the non-celluliferous face of a frond, showing the character of the branches and 
dissepiments, their comparative size and mode of growth. (X 6.) 
A portion of the eelluliferous face of the same specimen, showing the form and arrangement of the 
cell apertures, and the comparatively strong nodes along the middle of the branch. (X 6.) 
Upper Helderberg group. Falls of the Ohio river. 
Fenestella (Polypoka) orerescens. 
Page 170. 
A fragment, natural size. 
A portion of the non-celluliferous face of a frond enlarged to six diameters, showing the distribu¬ 
tion of nodes upon the surface. 
Upper Helderberg group. Western Neio York. 
F EN ESTELLA PE RT EN U IS. 
Page 106. 
An enlargement of a portion of the non-celluliferous face of a frond, showing the comparative 
size and character of the branches and dissepiments and their mode of growth. (X 6.) 
A portion of the eelluliferous face of the preceding, showing the form and arrangement of the 
cell apertures, the occasional larger apertures opposite the dissepiments and the prominent 
nodes along the middle of the branch. (X 6.) 
Upper Helderberg group. Falls of the Ohio river. 
Fig. 22. 
Fig. 23. 
Fig. 18. 
Fig. 19. 
Fig. 20. 
Fig. 21. 
