Fia 
PLATE VIII. 
Ch^tetes colliculatus. 
Page 11. 
1. An ovoid depressed-conical form, showing the mode of growth and the nodes covering the surface. 
Lower Helderberg group. Schoharie, N. Y. 
Fig. 2. A subhemispheric form showing the nodose character of the surface. 
Lower Helderberg group. Schoharie , N. Y. 
Fig. 3. An enlargement from the surface of fig. 1, showing the form of cell apertures, etc. 
Fig. 4. An enlargement from a vertical translucent section from specimen fig. 2. 
Ch,etetes monticulatus. 
Page 12. 
Fig. 5. A spheroidal-ovoid specimen, natural size. The nodes are well preserved on the upper part, but 
obscure on the lower part. 
Lower Helderberg group. Schoharie, N. Y. 
Fig. 6. An enlargement of the surface from fig. 5. 
Fig. 7. A translucent section from fig. 5, showing the irregular form of the cells, the transverse septa, 
and the laminae causing interruption in the continuity of the cells. 
Favosites sph^ericus. 
Page 9. 
See Plate 7. 
Fig. 8. A growth of this species upon Favosites HelcLerbergice, which continuing for some time is succeeded 
by Stromatopora, which in turn is followed by Favosites sphericus, and again by Stromatopora. 
