PLATE XXX. 



LiCHENALIA SDBSTELLATA. 



Page 78. 



See Plate 26. 



Fig. 1. A specimen, natural size, havinjr elevated tnaculs. 



Fig. 2. A specimen, showing the general asiiect of the species, the fonn and ai-i-angement of the maculae, 



and the large cellules immediately sun-ouuding them. 

 Fig. 3. One of the maculse, showing the cijntiguou.-J cell ai>ertui-e.s. (X 16.) 

 Fig. 4. A portion of the sui-face, showiiitr the cell apertui-es closed by opercula. (X 16.) 

 Fig. 5. Another portion, showing the cell ai)Prtui"es. (X 16.) '".I'l 



Fig. 6. An enlargement of the oblique cell apertures, with a i)ortion of the cell tubes exposed. (X 16.) 

 Fig. 7. A portion of a frond, where the surface ha.>< l)een wora away, ."showing the intei-stitial pits. (X 16.) 

 Fig. 8. A portion of the surface, showing cell ajierlui-eswith elevated margins and obscure dehticulAtions. 



(X 16.) • ' ' 



Fig. 9. A vertical section, showing cell tubes and septate intercellular tubuses. 

 Fig. 10. A vertical section fi-om (inothfer fr<iiid.' showing the cell tubes mftre- fclosely ari-anged than in the 



preceding. 

 Fig. 11. A (lortion of the surface, showing some of the cell apertures, closed and preaeuting a pustulifocm 

 1, aaytect. fX 16.) • i 



Upj>er Helderberg gi-oup. Falin of the Ohio rieer. 



LiCHP.NALIA (PiLEOTRYPa) UENTICOLATA. 



See Plate 2ti., 



Fig. 13. A specimen, natural size, showing the general appearance of the species, the form and arrange- 

 ment of the maculte etc. 

 Fig. 13. A portion of the surface of the preceding, showing the form and arrangement of itie cell Apertures. 



(X 6.) '..'..'.'.' ' 



Fig. 14. An obli(iue view of a portion of the sarfacej showing the height and form of the elevated cell 

 margins. (X 6.) . n . . - ,. ,, /<.^^ ^ 



Fig. l.l. Two views, each one of a single cell apertur^ apen obliquely from above, and greatly enlarged, 

 showing more distinctly the ap(>earance of itie elevated cell margins. The figure has been 

 inadvertently shaded between the cells which should be i-epresented as two distinct figures. 



Fig. 16. Front and lateral views of the elevated cell margins. (X 16.) 



Fig. 17. A portion of the surface of a frond, showing the form and arrangement of the cells and the denti- 

 culated cell margins. (X 16.) 



Pig. 18. Three cell apertures much enlarged, to show the vai-iation in their fomi and margins. 



Fig. 19. A vertical section of a i)ortion of a frond, showing oblique cell tul)e8. 



Fig. 20. A vertical se<;tiou from another frond, showing the cell tubes and intereellular vesicular structure. 

 Upper Helderberg group. Pall8 of the Ohio river. 



^% 



