

1^' 



PLATE XXIX. V, - 



SCALARIPORA SUBCONCAVA. 



Page 100. 

 Fig. 1. A fi-ag-mciit, natural size. 



Fig. 2. A transvei'se section of a branch, showing its form, the celluliferoua scala;, the internal radiating 

 mesotheca, and the intei-cellulai- vesicular structure. (X t>.) i-i-.r'l L' 



Fig. 3. An eulargement of one of the faces, showing the scalae and the form and ai'raugement of the cell 

 apertui-es. (X ti.) 



Ujijier Heldei'berg group. Falls of the Ohio rioer. 



SCALAKIPOKA SCALAKIFORUIS. 



I'llffO 100. 

 Fig. 4. A fragment, natural size. 



Fig. 5. An enlargement of one of tli« fa<es of a fragmfiit. shuw'niir th'' scale ami tlic form and arrange- 

 ment of the cell apertui-es. (X H) 



Fig. 6. A view, looking directly upon one of the angles, siiiowiii),' the angular margins, the scahe of two of 

 the faces and the form and arrangement of the cell a|>erturef. (X 6.) 



Fig. 7. An obliipie view of one of the faces, showing the concavity of the sui-face, the arrangement of the 

 external celiulifei-ous sc;il:u, and the form ami diaivMitioa of the cell apertures (X (>.) 



Fig. 8. A transverse section of a lirauch. showing the foinn of Hie cellaliferous seals, the radiating meso- 

 theca and the divergent cell tubes. (X 6.) 

 I Upi>er Helderberg group. Falls of the Ohio river- 



•■luiii ■f>gri I 



Prismopora TRIQUETRA. ^ i^i 



 I !/ Page W. ol J ASYUiUMIOacO 



See Plate S8. 

 Figs. 9, 10, 11. Fragments, natural size, showing the ordinary variations in form and appearance. 

 Fig. 12. A portion of one of the faces of a frond enlarged, showing the non-cellulifei-uns margiiis, and the 



foi-m and arrangement of the cell aiM'rtui-es. (X 6.) 



Pig IS. kn enlargement, of the sinface from near the margin of one of the faces, showing the very 



(iblii|ue cell apertures, with prominent denticulate margins ; the denticulations giving to the 



apertures a subtrilobat/> form. (X 18.) " •"■nr  i i 



Vxg. 14. An enlargement from another specimen, showing the ranges of apertures separated by pi-oi'ninent 



""" ridges; the denticulations of the cell margins are much more' conspicuous than in figui-e 13. 



(X6.) 

 Fig. 15. A transverse section of a branch, showing the concave faces, the radiatityg^ plates or mesothecse 

 and the upnght portion of the cells. 



Upper Helderberg group. Pallii of the Ohio river. 



PrISMOHIRA PAUCIRA.MA. *'° '''''?'' 



I 'age M. 



See Plate 28. 

 Fig. 16. A. fragment, natural size. 



Fig. 17. An enlargement of one of the faces, showing the form and arrangement of the cell apertures. ( X 6. ) 

 Upper Helderberg group. Onondaga Valley, Oitondaga County, N. Y. 



