PLATE XXV— Continued. 



TrKMATOPORA (TrEMATELLA) ANNUIiATA. 



, , , Paj?e S9. 



Ii') -id; lo Jnnm-rjau«Tta i>iir _ 



See Plate 26. 

 Vig. 23. A Rpeciraen, natnrnl size. 



ITpjior HeMt'i-berg' group. Fall* of the Ohio river. 

 Kg. 23. A poi-tion of tho surface of the preceding, showing the polygonal and closely arranged cell 

 ai^rtures. (X 18.) 



TROPIUOrOKA NANA. 



Page 71. 

 Pig. 25. A specimen, natural size, associated with Anfopora and FeneMella. 



Fig. 20. A i>ortion ( X 18) ahowinj; the form mid iiiTanfrement of the cell ai>ertui-es and the undulating 

 longitudinal ridges. 



Upper Helderberg gi-oup. 



TREM.4TOPORA (OrTHOPORa) REGITLARIS. 

 Page 91. 

 See Plates 11, 13, 23 and 26. 

 Fig. 27. A fragment, natural size. 



Pig. 28. A iK)rtion (X 6) showing rows of granules between the cell ajiertures. 

 Upper Helderberg group. Falls of the Ohio river. 



■'""«■"" ' 



Trematopora (Orthopoka) RHOMBIFERA. ; 



Page 71. 

 See Plates 11, 23 and 26. ir lo u.iU-khj .. 



Fig. 29. A specimen, natural size, showing an unusual mode of branching. ^) .« .'gft ni 



Upper, Helderberg group. Faili of the Ohio i-iver. 



•■■ -1 NeMATAXIS FIBK08U8. 



Page 74. 



Fig. 30. A .sjiecimen, natural size, imbedded in the rock, and fractured so as to show t^ie|^Jtpraal structure 



and also the mode of branching. alljiw 



Upper Helderberg group. 



Fig. 31. A portion of another specimen. The cell apertures are obsolete and the surface is marked by 



broad, somewhat irregular, longitudinal striations. (X 6.) 



Upper Helderberg group. iMnfosKp V 



Fig. 32. A portion of the surface of another specimen, pi-esenting charactei-s similar to those in tig. 31, 

 but having finer and more regular striations. (X 6.) 



Upper Helderberg gi-oup. , , 



Fig. 33. A portion of a specimen broken below and showing the angular cell iiibes. (>^ IB.) 



Upper Helderberg gi-oup. I«;|}(1' 



Fijf. 34. A portion of a specimen, showing the oval cell apertures aiTang«d in regular longitudinal rows 

 lo lioilJ'ii and macule destitute of cell apertures. (X 6.) ' "- .("I ."I ,'''1 f-v'i 



Uppei- Hehlerberg group. '''■ 



-Fig. 3S. A portion of fig. 30, showing the cell tubes and the fibrous stmcture near the surface. 

 Fig. 36. A pcfrtion of the interior of a specimen, showing the dii-ection of the cell tubes. (X 6.) 



