PLATE XVI. 



Zaphrentis Canadensis. 

 Fig. 1. A longitudinal section through the center, showing the tabulae. 

 Fig. 2. A longitudinal section from near the side of the corallum, showing 



the vertical lamellae. 

 Fig. 3. A transverse section through the cup, showing the number and size of 

 the lamellae and the position of the fossette. 



Hudson ffiver group, Ohio. 



Heliophyllum Halli. 

 Fig. 4. A vertical section through the center. 



Fig. 5. A transverse section through the lower part of the cup, showing the 

 lamellae and vescicular tissue. 



Hamilton group, N. Y/ 



Cystiphyllum Americanum. 

 Fig. 6. A longitudinal section of a corallum, showing the characteristic 

 structure. Hamilton group, N. Y. 



CVATHOPHYLLUM RUGOSTJM. 



Fig. 7. A horizontal section of a mass of corallites. 



Upper Helderberg group, Falls of the Ohio. 



MlCHELINIA STYLOPORA. 



Fig. 8. A vertical section of a large mass showing the usual characters of 

 the species. Hamilton group, N. Y. 



Tetradium Ontario, n. sp. 

 Fig. 9. A horizontal section showing the form of the tubules in a very satis- 

 factory manner. 



Clinton group, Shore of Lake Ontario. 



Stromatopora nodulata ? 

 Fig. 10. A horizontal section of a portion of a specimen. 

 Fig. 11. A vertical section of the same species. 



Upper Helderberg group, Kelly's Island, Ohio. 



These illustrations of translucent sections of fossil corals are given to ac- 

 company the paper on the " Machinery and Methods of Cutting Specimens of 

 Rocks and Fossils " at the State Museum, pp. 121-124. The figures show in 

 a very satisfactory manner the structure of the specimens, and express the 

 value of similar sections in the study of fossils. 



Ctenacanthus Wrighti. 

 Page 206. 

 Fig. 12. Lateral view of the specimen described. 

 Fig. 13. A small portion enlarged to show the surface sculpturing. 

 Fig. 14. An outline showing the form of a transverse section. 



Chemung group, Yates Co. , N. Y. 



