PLATK XJCXI— Coiitlnueii. 

 Fig. 24. An oblique view of the surface, showing' the projecting po8t«rior margins of the cell aper- 

 tures. (X 6.) 

 Fig. 25. A vertical section of a thin lamina i^Ci-usting a Fbnkstklla, and showing prominent posterior 



cell margins. (X 6.) " ••■-('■' 



Fig. 26. A portion of the surface of a specimen enlarged, showing the denticulate peristomes at right 



angles to the general surface, with the interme<iiate space bullat«. (X 18.) 



Jflg, 27. An enlargement of the surfa<«! of a si>ecimen where the cell apiM-tnitis, on the lower part of the 



.,ii' •  fig^ii-e, are very oblique, while in the upper poi-Uon they are nearly rectangular to the surface, 



with a liuUate intermediate space. This latter featui-e is obscurely shown on some parts uf 



the Buiface where the cells are oblique. , / 



nj .a»B«]s ijiliilDpper Helderberg group. .PbUs of the Ohio river. itisv A .8 .^i'-I 



'■ ■-'■ ' .Jioq A .r .f^'i 



LiCHENALIA LUNATAV'Nratt*. ■TUBULATA;"t-'9qs Il»n9lna« A .8 .%n 

 Page 78. V, noiHor, / 



Fig. 28. A fragment of a tubular specimen, natural size. 



Fig. 29. An enlargement of a portion of the preceding, showing the form and ain-angement of the den- 

 ticulate apertui'es. (X 6.)  . > . 



Upper Helderterg group. Fallt of the Ohio river. 



i A or .gi^ 



I'M V. rv-ri! LlOHENALIA (PiLEOTHYPA) CUVULATA. A .U .-^n 



«». Page a. ' "' '""" '>■ -^^ -"^"^ 



ftg. 30. A fragment of a tubular ramose form, natural size. 



Fig. 31. A portion of the surface enlarged, showing one of the monticules and adjacent cell apertures. 

 Fijr. 32. A portion of the surface further enlai-ged, showing an irregular disj^osition of the cell apertures, 

 '■ ' marked by the prominent peristomes which are excessively developed on the posterior side, 

 and the intermediate nodulose sui-face. (X 18.) 

 Fig. 33. A vertical section, showing the open cells and the i-egularly septate mlei'cenular space. (X 6.) 



Upper Helderberg group. Falls of the Ohio river. 



.-!;, . . / ; ;/ /"riruJ 



PhRACTOPORA CRISTATA Vur. LINKATA. 



Page 99. '■■ •''•' •«'•' 



Fig. 34. A fragment, natui-al size. '■ fl ■a'''! 



Fig. 36. An enlargement of the surface of the preceding, showing the character of the cell apertures and 



the narrow slightly elevated ci-ests traversing the surface. (X B.) .. • 



Upper Helderberg gitmp. FblU uf the Ohio n'wKi'l'l'»H ■t'iqrfj 



.A.ZJl.niFHKACTOPORA CRLSTATA. 



PBg« 99. 

 Fig. 36. A portion of a ft-ond, natui-ai size. ,,, ,„.,(,,,,r, 



Fig. 37. An enlargement fi"om the surface of the preceding, showing the ch^'SAter. i of the cell aper- 

 tures. iX 6.) . , , , 

 Pi^. 38. A section through the carins, showing the radiating mesotheca, the cells and intereellular struc- 



*"••«■ (X "■> „i, .! ;.il i..,(q i 



Upper Helderberg group. Falls of the Ohio river. 



.HIV _ ■• f ■,; iii:i.i''l ' I 1/ 1 , iiJ. 



LiCHENALIA ALTERNATA. 



Page 80. ■.-. Ijnift«ii ,lnMiT^i1 A .tSi .■^n 

 Fig. 3fl. A fragment, natural size. .,,i. ■> : / ...i . : ., 



Tig. 4p. A portion of the surface enlarged, to show the character and arrangement of cell apertures. (X 6.) 



Fig. 41. A portion of the surface still furthei' enlarged and presenting a somewhat diflerent aspect of the 



loh-jlxs mU P*" apertures. ,,.„,,.,„.„„ .,^(„..;^.. , ..i„il;-M,.-.-.^- ■.,[■ 



Upper Helderberg group. Fnlls of the Ohio river. ^^ jj^ ^^. .j ^ 



