PLATE LXI. 



Stictopora granifera. 



Page 257. 

 Fig. 1. A fragment of a frond, natural size, showing wide branches, much enlarged before bifurcation. 



Hamilton grouj). One mile north of Pavilion Village, Genesee county, iV. Y. 

 Fig. 2. An enlargement of a portion of another fi-ond ha\'ing narrower branches. 



Hamilton group. North Bristol township, Ontario county, N. Y. 

 Fig. 3. An enlargement, showing the cell apertures obscured by the granulose striations. (X 6.) 

 Fig. 4. An enlargement, showing the form and disposition of the cell apertures, which are unusually 

 distinct in this specimen. (X 6.) 



Hamilton group. I^l-brook, four miles east of Canandaigua lake, N. T. 

 Fig. 5. An enlargement, showing the cell apertures with granulose peristomes, and intermediate striae. 

 (X 18.) 



Hamilton group. York, Livingston county, N, Y. 

 Fig. 6. An enlargement of transverse sections of two fronds. 



Ptilodictya parallela. 



Page 270. 

 Fig. 7. A fragment of a frond, natui-al size. 



Fig. 8. An enlargement from the pi-e(!eding, showing the form and arrangement of the cell apertures and 

 the longitudinal striations. ( X 6.) 



Hamilton gi-oup. Fall-brook, four miles east of Canandaigiia lake, Ontario county. N. Y. 



Ptilodictya plumea. 



Page 271. 

 Fig. ft. A part of a frond, natural size, showing the manner of growth, and the frequent monticules of 



the surface. 

 Fig. 10. An enlargement from the portion of the frond imme<liately above fig. 11, showing oval cell aper- 



tui-ea between the longitudinal striations. (X 18.) 

 Fig. II. An enlargement of the base of the spe<!imen fig. 9, showing the truncate apex, and striated 



portion above. (X 18.) 

 Fig. 12. An enlargement from the same frond, showing the form and disposition of the cell apertures, and 



the elevate<l, granulose interme<liate space. (X H.) 



Hamilton group West Hamburg, Brie county, N. Y. 



Ptilodictya retiformis. 



Pace 272. 

 Fig. 13. An enlargement, showing the form and disjioeition of the cell apertures and the i-eticulate appear- 

 ance of the Bui-face. (X 6.) 



Hamilton group. Alden, Brie county, N. Y. 



Stictopora lihata. 



Page2S0. 

 Fig. 14. A fragment, natural size. 

 Fig. 15. An enlargement from the preceding, showing the small cell apertures and broad longitudinal 



ridges. (X 6.) 

 ¥ig. 16. An enlargement of a narrower form, with lesa prominent longitudinal ridges. (X 6.) 

 Hamilton group. Darien Centre, N. T. 



