PLATE I. [Assembly 



Fossils of the Potsdam sandstone. 



1. LiNGULA ANTIQUA ( page 36). 



Fossils of the Chazy limestone. 



2. Raphistoma staminea, upper surface and profile. 



3. AsAPHUS (tlie caudal portion of the animal). 



4. Btjcania sulcatina, profile outline. 



5. — — front view. 



6. SCALITES ANGULATUS (p. 40). 



*7. CoLUMNARiA ALVEOLATA (of the Black-rlver limestone). 



8. Raphistoma striata. 



9. Orthis. 



10. DiSCINA DEFORMIS. 



11. Maclurea magna, upper surface ( p. 30). 



* This '^ Columnaria" is one of the Corals which grow in crowded masses, like the 

 cells of honeycomb. It is sometimes found in masses of a ton or more in weight. 



] 



