PLATE LVI—Continued. 
Trematopora (Orthopora) tortalinea. 
Page 180. 
Fig. 9. An enlargement, showing the form and disposition of the cell apertures, and the sinuous, granu- 
lose ridges separating the ranges of apertures. (X 18.) 
Hamilton group. West Hamburg, Erie county, N. Y. 
Trematopora (Orthopora) lineata. 
Page 181. 
See Plate 55. 
Fig. 10. An enlargement, showing the form and disposition of the cell apertures, the extremely thin. 
slightly elevated peristomes, and the prominent, granulose ridges separating the ranges of 
apertures. (X 18.) 
Hamilton group. ( Vest Hamburg, Erie county, N. Y. 
Trematopora (Orthopora) immersa. 
Page 185. 
Fig. 11. An enlargement, showing the form and disposition of the cell apertures, and the character of the 
interapertural space. (X 18.) 
Hamilton group. West Hamburg, Erie county, N. Y. 
Trematopora (Orthopora) interplana. 
Page 186. 
Fig. 12. An enlargement, showing the form and disposition of the cell apertures, the slight peristomes, 
and the flat, granulose, interapertural space. (X 18.) ■ 
Hamilton group. Western New York. 
Trematopora (Orthopora?) transversa. 
Page 187. 
See Plate 55. 
Fig. 13. An enlargement, showing the form and disposition of the cell apertures, and the flat, granulose 
interapertural space. (X 6.) 
Fig. 14. A still farther enlargement, showing more distinctly the characters illustrated in fig. 13. 
Hamilton group. West Hamburg, Erie county, N. Y. 
Trematopora (Orthopora) e eon gat a. 
Page 183. 
See Plate 55. 
Fig. 15. An enlargement, showing the form and disposition of the cell apertures, the extremely thin peri¬ 
stomes, and the granulose interapertural space. (X 18.) 
Hamilton group. Near the head of Owasco Lake, N. Y. 
Trematopora (Orthopora) bispinulata. 
Puge 182. 
See Plate 55. 
Fig. 16. An enlarg-ement, showing elongate-oval, regularly disposed cell apertures, the alternating nodes 
and prominent longitudinal ridges. (X 18.) 
Fig. 17. An enlargement, showing somewhat broadly oval cell apertures, regularly disposed in longitudi¬ 
nal rows, with two nodes between each two adjacent apertures, and sinuous longitudinal ridges. 
(X 18.) 
Hamilton group. Darien Centre, N. Y. 
Fig. 18. An enlargement, showing indistinct cell apertures, prominent nodes and interrupted longitudinal 
ridges. (X 18.) 
Hamilton group. Moscow, Livingston county, N. Y. 
Acanthoclema scutulatum. 
Page 190. 
See Plate 55. 
Fig. 19. An enlargement, showing regularly disposed cell apertures, and longitudinal ridges coalescing 
between the apertures, with nodes at their junction. (X 18.) 
Fig. 20. An enlargement from a slightly macerated specimen, showing regularly disposed cell apertures, 
strong longitudinal ridges, and a node and pit between each two adjacent apertures. (X 18.) 
Hamilton group. West Hamburg, Erie county, N. Y. 
