Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
PLATE LXII—Continued. 
Tacniopora extgua. 
Page 203. 
15. A fragment of a frond, natural size. 
Hamilton group. Near Dresden, N. Y. 
16. An enlargement, showing the usual appearance of the frond, and the form and disposition of the 
cell apertures. (X 6.) 
Hamilton group. Greneseo, Livingston county, N. Y. 
17. An enlargement of a portion of a narrower frond, showing only four ranges of cell apertures. 
(X 6.) 
Hamilton group. Four miles east of Canandaigua lake, N. Y. 
18. An enlargement of -a transverse section, showing the form and mode of growth of the cell tubes. 
(X 6.) 
19. An enlargement, showing the recumbent part of the cell tubes and their increasing obliquity 
to the longitudinal axis of the branch. (X 6.) 
Hamilton group. Eighteen-mile-creek, Erie, county, N. Y. 
20. A transverse section of a branch, showing the intercellular, vesiculose tissue. (X 6.) 
21. An enlargement of a transverse section from another frond, showing a much stronger carina than 
in fig. 20. (X 6.) 
Hamilton group. Dresden, N. Y. 
22. A fragment, natural size ; the main branch is triangular, the lateral branches flattened. (X 6.) 
23. An enlargement, showing two sides of the triangular main branch, and flattened lateral branches. 
(X 6.) 
24. An enlargement from fig. 22, showing a concave face of the triangular main branch, and the form 
and arrangement of the cell apertures. (X 6.) 
25. An enlargement from fig. 23, showing two faces of the triangular main branch, and two flattened 
lateral branches. (X 6.) 
26. A transverse section of the triangular main branch. 
Hamilton group. From loose specimens of the rock at Vnadilla Forks, Otsego county, N. Y. 
Semiopora bistigmata. 
Page 262. 
27. A fragment of a frond, natural size. 
28 An enlargement, showing the form and arrangement of the cell apertures, the interapertural pits, 
and the striated non-celluliferous margins. (X 6.) 
29. An enlargement of a transverse section. (X 6.) 
Hamilton group. West Williams, Ontario, Canada. 
