A. M. Miller — Ordovician Cynthiana Formation. 655 



The writer is not equally familiar with the lower Ordovician 

 section of the Nashville area in Tennessee, but a visit made 

 to that region several years ago enables him to identify in the 

 uppermost rocks within the limits of the city of .Nashville 

 typical Cynthiana as it is developed in Central Kentucky. 

 Here it lies above the " Upper Dove Limestones" of Safford, 

 which are undoubtedly the equivalent of the Salvisa of Ken- 

 tucky. 



It is therefore evident from the foregoing that structurally 

 the Cynthiana is a well-defined member of the Cincinnatian 

 series, and that it lies between two disconformities — the 

 lower more marked than the upper. In its exposures in 

 the Blue Grass areas of Kentucky and Tennessee it everywhere 

 furnishes a soil of good quality but inferior to that resulting 

 from the Lexington limestone. It is, however, much superior 

 to that formed by the overlying Eden. 



Faunally also it is distinct. The characteristic upper Lexing- 

 ton limestone (Bigby) brachiopods — Rhynchotrema incequi- 

 valve. Hebertella franTcfortensis {borealis of some authors)^ 

 do not pass up into it. A list of the most abundant fossils of 

 the Cynthiana contains the following : 



Corals 



Columnaria alveolata Hall (stellata of some authors). 

 Hydroids 



Selenopora irregularis Ulrich. 

 Stromatocerium sp. ? 

 Crinoids 



Glyptocrinus sp. ? Ioerinus subcrassus M. & W., Licheno- 

 crinus crater if ormis Hall. 

 Bryozoans 



Aspidopora calycula James, Ceramporella ohioensis Nich. 

 (doubtful identification), (Jonstellaria emaciata IT. &. B., 

 Constellaria fischeri Ulrich, Crepipora spatiosa Ulrich, 

 Eridotryp>a briareus Nich. (very characteristic of this forma- 

 tion), E. mutabilis Ulrich, Escharopora p>onclerosa Ulrich, 

 Haterotrypa parculipora IT. & B., Homotrypella norwoodi 

 Nickles, Peronopora miller i Nickles, Petigopora sp. ?, Praso- 

 pora sp. ? 

 Brachiopods 



Hebertella maria parkensis Foerste, Hebertella sinuata Hall, 

 Orthorhynchnla linneyi James, Platystrophia colbyensis ? 

 Rafinesquina winchesterensis Foerste, Zygospira modesta 

 Hall. 

 Pelecypods 



Allonychia flanaganensis Foerste, Byssonychia radiata Hall, 

 Byxsonychia intermedia M. & W., Ctenodonta sp. ? 

 Orthodesma sp. ? 



