PLATE XXX—Continued. 
Fistulipora lamellata. 
Page 87. 
Fig. 21. A portion of the surface, showing the form and arrangement of the cell apertures and intercel¬ 
lular pits. (X 6.) 
Fig-. 22. A portion of the same. (X 18.) 
Fig. 28. The surface of another specimen, in which the intercellular pits are obsolete. (X If.) 
Upper Helderberg group. Onondaga Valley, N. Y. 
Lichexalia (Odontotryipa) alyeata. 
Page 85. 
Fig-. 24. A specimen, natural size, incrusting a Fenestella. 
Fig. 25. A portion of the surface of the preceding, showing the form and arrangement of the cell apertures. 
(X 6.) 
Fig. 26. A front view of the cell apertures, showing theij- form and the elevation of the margins. (X 6.) 
Fig. 27. A portion of their surface. (X 16.) 
Upper Helderberg group. Falls of the Ohio river. 
Lichenalia (Pileotrypa) granifera. 
Page 84. 
Fig. 28. A specimen, natural size. 
Fig-. 29. A portion of the surface from the preceding, showing the form and arrangement of the cell aper¬ 
tures and the interapertural granules. (X 6.) 
Fig. 80. A few of the cell apertures, showing more distinctly the elevated margins and the granulated 
interapertural space. (X 18.) 
Fig. 81. A vertical section of a portion of a frond, showing the constricted and septate cell tubes and inter¬ 
mediate septate tubuli. 
Upper Helderberg group. Falls of the Ohio river. 
