Table of Contents. 



PAGE 



Letter of Transmittal 3 



Introduction 9 



Genera! , 9 



Geological History 11 



Table ot Ordovician -formations 15 



Nomenclature and notes on the table 16 



Ordovician 1C 



Cincinnatian 16 



Richmond 16 



Saluda and Arnheim 16 



Versailles 17 



Maysville 17 



Edsn 17 



Winchester and Point Pleasant 18 



Mohawkian 19 



Stratigraphy 19 



Mohawkian series 20 



Lexington group 20 



Cincinnatian series 22 



Winchester group 22 



Eden group 25 



List of Eden bryozoa 28 



Maysville group 29 



List of Maysville bryozoa 30 



Subdivisions of the Maysville 32 



Mount Hope beds 32 



Fairmount beds 32 



Bellevue beds 33 



Corry ville beds 34 



Mount Auburn beds 34 



Arnheim beds 35 



Richmond group 36 



List of Richmond bryozoa 37 



Subdivisions of the Richmond 38 



Waynesville beds, or lower Richmond 38 



Versailles beds, or middle Richmond 39 



Saluda beds, or upper Richmond 40 



Descriptions of species 41 



1. From the Lexington group 41 



Prasopora simulatrix Ulrich 41 



Callopora multitabulata (Ulrich) 42 



Dekayella trentonensis (Ulrich) 42 



178676 



