PLATE XXXII. 



LiCHENALIA OVATA. 



Page 80. 



Fig. 1. A fragment of a frond, natural size. 



Fig. 2. An enlargement of a portion of the sui-face, to show the form and arrangement of the cell 

 apei-tures. (X 6.) 



Fig. 3. A portion of the surface still further enlarged, showing broadly ovate cell apertures with the 

 denticulations more or less distinct. (X 18.) 



Fig. 4. An enlargement, showing the apertures more nearly circular and u.sually destitute of denticu- 

 laHons. (X 18.) 



Fig. 5. A section, showing the vertical non-septate cells with the intercellular space regulai-ly sep- 

 tate. (X 6.) 



Upper Helderberg group. fiUU of the Ohio river. 



LiCHENALIA BISTRIATA. 

 Pago 79. 



Fig. 6. A fragment of a frond, natural size. 



Fig. 7. A portion of a surface of fig. 6 enlarged, showing one of the maculse and adjacent cells. (X 6.) 



Fig. 8. An enlargement from a surface which hae been weatbei-ed, pai-tially obliterating the peris- 

 tomes. (X 18.) 



Fig. 9. An enlargement, showing the character of the cell apertures when well-preserved. (X 18.) 



Fig. 10. A vertical section, showing the cells without septa, the intermediate space being vesiculose or 

 regularly septate. (X 6.) 



Pig. 11. A fragment of another s^iecimen, natural size. 



Fig. 12. An enlargement of the surface which has been somewhat weathered, showing the lunate form of 

 the apertures. (X 6.) 



Fig. 13. A portion of the surface enlarged, showing the character of the cell apertures when in a perfect 

 condition. (X 18.) 



Fig. 14. A vertical section, showing the cells without septa, with the intermediate space regularly 

 septate. (X 6.) 



ITpjier Helderberg group. Palls of the Ohio ririer. 



FiSTULIPORA INTERCELLATA. 

 Page 87. 

 Fig. 15. A fragment of a specimen, natural size, incrusting a Fenbstklla. 



Fig. 16. A portion of the same enlarged, showing the foi-m and arrangement of the cell apertures and 

 int»'rmediate pits or mesopores. The surface is partially covered by other organisms. (X 6.) 

 Fig. 17. A fragment of another specimen, natural size. 

 Fig. 18. An enlargement of the preceding, showing the cell apertures larger and more closely arranged 



than in fig. 16. (X 6.) 

 Fig. 19. A portion of the specimen 6g. 17, still further enlarged, showing the character of the cell aper- 

 tures and the mesopores. (X 18.) 

 Pig. 20. A vertical section, showing the non-septate cells and the septate interspaces. 

 Upper Helderberg gi-oup. Falls of the Ohio river. 



