PLATE III. [Assembly 



Fossils of the Trenton limestone. 



TRILOBITES. 



1. murchisonia gracilis. 



2. holopea paludin^formis. 



3. Cameroceras trentonense (Orthoceras arcuoliratum). 



4. Orthoceras vertebrale. 



5. Trinucleus concentricus, detached head (p. 47). 



6. Dalmania, detached central part of head. 



7. Ceraurus pleurexanthemus, detached head ; " cheeks" gone. 



8. Calymene senaria, entire, bjit distorted. 



9. Ill^nus crassicauda. 



10. Sph^roma bumastiformis : a living crustacean from the South 



seas, somewhat resembling the trilobites. 



11. ISOTELUS GIGAS, Or ASAPHUS PLATYCEPHALUS, perfect. 



12. iLLiENUS TRENTONENSIS, perfect. 



