26 PLATE XII. [Assembly 



Fossils of the Marcellus shale. 



1. Orthoceras subulatum. 



2. Strophomena setigera. 



3. s. mucronata. 



4. s. pustulosa. 



5. avicula mucronata. 



6. A. L^vis. 



7. a. equilatera. 



8. Orthis nucleus. 



9. DiSCINA MINUTA. 



10. Tentaculites fissurella. 



11. Atrypa limitaris. 



Fossils of the Hamilton group ( p. 67). 



CORALS. 



12. Strombodes simplex ( a small parasitic coral or bryozoon is at- 



tached on it). 



13. Same, end or cup. 



14. Strombodes helianthoides. 



15. S. DISTORTUS. 



16. S. RECTUS. 



17. Ctstiphyllum cylindricum. 



18. Same? with another kind of coral (Aulopora) attached. 



