PLATE XXVIII—Continued. 
Stictopora FRUTICOSA. 
Page 92. 
Fig-. 12. A specimen, natural size, showing the mode of branching and arrangement of cell apertures. 
Fig. 13. An enlargement from a portion of fig. 12, the surface being well preserved, showing the form and 
arrangement of cell apertures, and the ornamentation of the intercellular space and of the non- 
celluliferous margin. 
Fig. 14. An enlargement from a portion of fig. 12, the surface being much weathered. The cell apertures 
are largei-than those of fig. 13, and apparently more irregularly arranged. The ornamenta¬ 
tion of the surface is nearly or quite obsolete - ; 
Upper Helderberg group. New York. 
Stictopora rigida. 
Page 91. 
Fig. 15. A specimen, natural size, showing the rigid form and mode of branching. 
Fig. 16. A portion of fig. In, enlarged, showing the form and arrangement of cell apertures, the striated 
longitudinal ridges and the non-celluliferous margin. (X 6.) 
Upper Helderberg group. Near Le Iioy, N. Y. 
Stictopora semistriata. 
Page 95. 
Fig. 17. A specimen, natural size, regularly bifurcating. 
Fig. 18. A specimen, natural size having lateral branches. 
Fig. 19. A portion of a specimen enlarged, showing the form and arrangement of cell apertures, and 
strong longitudinal ridges. (X 6.) 
Fig. 20. An enlargement of a portion of another specimen, on which the cell apertures are apparently 
more irregularly arranged, and the longitudinal striations are obsolete. 
Upper Helderberg group. Near Le Hoy, N. Y. 
Stictopora Gilberti. 
Page 90. 
See Plate 27. 
Fig. 21. A specimen, natural size, showing- the form and mode of branching. 
Fig. 22. An enlargement of a portion of fig. 21, showing more plainly the mode of bifurcation, the non-cel- 
luliferous margins, the form and arrangement of cell apertures, and the longitudinal striations 
or ridges. (X 6-) 
Upper Helderberg group. Falls of the Ohio river. 
Stictopora ovatipora. 
Page 93. 
See Plate 27. 
Fig. 23. A specimen, natural size, showing- the form and mode of growth near the base. 
Fig. 23a. An enlargement of fig. 23, showing the base, mode of branching, non-celluliferous margin, form 
and arrangement of cell apertures, and the strong longitudinal ridges. (X 6.) 
Upper Helderberg group. Falls of the Ohio river. 
Stictopora invertis. 
Page 94. 
Fig. 24. A specimen, natural size, showing the form and mode of branching. 
Fig. 25. An enlargement of a jiortion of fig. 24, showing the non-celluliferous margin, and the form and 
arrangement of the cell apertures. 
Fig. 26. A vertical section from fig. 24, showing the mesial septum and the form and manner of growth 
of the cell tubes. 
Upper Helderberg group. New York. 
