PLATE LV—Continued. 
Fig-. 
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Fig. 
Fig. 
TREMATOPORA (ORTHOPORA?) TRANS VERSA. 
Page 187. 
See Plate 56. 
12. An enlargement of a longitudinal” section, showing the manner of growth of the cell tubes, and 
the interapertural space. (X 6.) 
Hamilton group. Hamburg , Lake Erie shore, Erie county, N. Y. 
TREMATOPORA (OltTHOPORA ? ) ORBIPORA. 
Page 188. 
See Plate 56. 
13. An enlargement, showing the form and .disposition of the cell apertures, and the character of the 
interapertural space. (X 6.) 
14. An enlargement of a longitudinal section, showing the manner of growth of the cell tubes, and 
the intercellular space. (X 6 ) 
Hamilton group. Near Canandaigua lake, N. Y. 
Acanthoclema scutulatum. 
Page 190. 
See Plate 56. 
15. An enlargement of a longitudinal section, showing the filiform axis, the cell tubes and the inter¬ 
mediate tubuli formed by the nodes. (X 6.) 
Hamilton group. Near Dresden, N. Y. 
16. An enlargement, showing the form and disposition of the cell apertures, the alternating nodes, 
and the longitudinal ridges not coalescing between the cell apertures. (X 6.) 
Hamilton group. Western New York. 
17. An enlargement, showing the form and disposition of the cell apertures, the longitudinal ridges 
coalescing between the cell apertures, and the prominent nodes at the point of junction. (X 6.) 
Hamilton group. Near Dresden, N. Y. 
Acanthoclema IIamiltonense. 
Page 191. 
18. An enlargement, showing the irregular form and disposition of the cell apertures; interapertural 
pits obsolete. (X 6.) 
19. A still farther enlargement, showing more plainly the characters represented in tig. 18. (X 18.) 
20. An enlargement, showing the form and disposition of the cell apertures, and the sinuous longi¬ 
tudinal ridges. (X 6.) 
Hamilton group. West Williams, Ontario, Canada. 
21. An enlargement, showing the regular disposition of the cell apertures, the interapertural pits, 
and the sinuous ridges. (X 18.) 
Hamilton group. West Hamburg, Erie county, N. Y. 
22. An enlargement of a longitudinal section, showing the intercellular structure ; the section is a little 
to one side of the center of the branch, and consequently the filiform axis is not seen. (X 6.) 
23. An enlargement, showing both a regular and irregular disposition of the cell apertures. (X 6.) 
24. An enlargement from a macerated specimen, showing the spiral arrangement of the cell aper¬ 
tures more distinctly than the longitudinal. (X 18.) 
25. A still farther enlargement of the specimen represented by fig. 23, showing more distinctly the 
irregular form and disposition of the cell apertures. (X 18.) 
26. An enlargement, showing large cell apertures regularly disposed, the interapertural pits, and 
their sinuous ridges. (X 18.) 
Hamilton group. West Williams, Ontario, Canada. 
Trematopora (Orthopora) bispin ulata. 
Page 182. 
See Plate 56. 
27. An enlargement, showing indistinct cell apertures, prominent nodes and interrupted longitudinal 
ridges. (X 6.) 
Hamilton group. Moscow , Livingston county, N. Y. 
28. An enlargement of a longitudinal section, showing the internal structure near the surface, the 
cell tubes and the intercellular tubuli formed in the course of growth by the hollow nodes. (X 6.) 
29. An enlargement, showing the form and regular disposition of the cell apertures, the interapertural 
nodes and the longitudinal ridges. (X 6.) 
30. An enlargement, showing a regular disposition of the cell apertures, and also a somewhat irregular 
order above. 
Hamilton group. Darien, Genesee county, N. Y. 
