PLATE LXn— Continue<l. 



T^NIOPORA EXIGUA. 



Pageaen. 

 Vig. 1&, A tn^gment of a frond, naturnl size. 



•""I"' '"<• •"••■' Hamilton gi-oup. Near Drenden. N. T. 

 Fig. 16. 'Ah enlargement, showing the usual appearance of the tVoml, and the form and disposition of the 

 cell apertures. (X 6.) 



Hamilton group. Qenexeo. TAvhigsffm county, N. ¥. 

 Fig. 17. An enlargement of a poi-tion of a narrower frond, showing only four ranges of cell apertures. 

 (X 6.) 



Hamilton gi-oup. Fhur mien east of CanaitdaigiM lake, iV. Y. 

 Fig. 18. An enlargement of a transverse section, showing the form and mode of growth of the cell tubes. 



(X6.) 

 Fig. 19. An enlargement, showing the recumbent part ef the cell tubes and their increasing obliquity 

 to the longitudinal axis of the branch. (X 6.) 



Hamilton grouj). Eightee7i-iidle-creek, Erie county, N. T.. , , i ^ , - 

 Fig. 20. A transverse section of a branch, showing the intercellular, vesiculosa tissue. (X 6.) 

 Fig. 21. An enlargement of a transvei'se section from another frond, showing a much stronger carina than 

 in fig. 20. (X B.) 



Hamilton group. Dresden, iV. ¥. 

 Fig. 22. A fragment, natural size ; the main branch is triangular, the lateral branches fiatteneil. (X 6.) 

 Fig. 23. An enlargement, showing two sides of the triangular main branch, and flattened latei'al branches. 



(X6.) 

 Fig. 24. An enlargement from Kg. 22, showing a concave face of the triangular main branch, and the form 



and aiTangement of the cell apertures. (X <5.) 

 Fig. 25. An eidargeincnt from fig. 28, showing two faces of the triangular main branch, and two flattened 



lateral branches. (X 6.) 

 Fig. 26. rt ti-ansvei-se section of the triangular main branch. 



Hamilton group. Fi-mn loose speciiaen.i of the rock at Vnadilla Forks, Otsego county, JV. Y. 



( 'r ., 



Semiopora bistigmata. 



Page 262. 

 Fig. 27. A fragment of a frond, natural size. 



Fig. 28 An enlargement, showing the form and arrangement of the cell apertures, the int»!rapertur{il pita, 

 and the striated non-celluliferouB margins. (X 6.) .\ >I .^j-j 



Fig. 29. An enlargement of a transvei'se sec;tioh. (X ti.) 



Hamilton group. West Williams, Ontario, Canada. 



