112 Cincinnati Society of Natural History 



mile northeast of Carlisle, specimens of Clitambonites occur, sug- 

 gesting the presence of the overlying Rogers Gap fauna. Farther 

 northeastward, toward Parks Hill, and, finally, south of Pleasant 

 Valley, the Orthorhynchula fauna occurs again, overlaid here by a 

 coarse-grained, massive limestone, called the Nicholas bed. 



For the richly fossiliferous, argillaceous, irregularly bedded 

 limestones, frequently weathering into the irregular fragments 

 called rubble, and containing Orthorhynchula linneyi, Hcbertella 

 parksensis, Platystrophia colbiensis, RaHnesqiiina zvinchesterensis, 

 Cycloncma varicosum, Constellaria eniaciata, Homotrypella nor- 

 woodi, Heterotrypa parvulipora, and numerous other species, the 

 term Millersburg limestone is proposed. It corresponds to the 

 most characteristic part of the Catheys of Tennessee, and has been 

 included in the Greendale division of. the Cynthiana in former 

 papers. Its base is formed by the All onychia horizon, between 

 Flanagan and Millersburg, and it is overlaid by the coarse-grained 

 Nicholas limestone south of Pleasant Valley, and the coarse- 

 grained limestone containing Clitambonites, south of Carlisle. 



It is the Millersburg member, more than any other division of 

 the Cynthiana formation, which contains the most frequent pre- 

 cursors of the Fairmount fauna, although precursors of this fauna 

 are found also in other divisions of the Cynthiana. The richly 

 fossiliferous exposures of the Cynthiana along the "belt line," in 

 the northeastern part of Lexington, suggest to me the Millersburg 

 rather than the Greendale fauna. Precursors of the Cynthiana 

 fauna occur also in other divisions, and the Cynthiana, as a whole, 

 may be regarded as an early introduction of the Fairmount fauna. 



This Millersburg or OrtJwrhynchula phase of the Cynthiana 

 formation is abundantly developed along the eastern side of the 

 Cincinnati geanticline, as far southward as the exposures west 

 of the Million tunnel, on the road to Valley View. Certain ele- 

 ments of this fauna are abundantly represented at Lexington, at 

 the railroad cut southeast of Harrodsburg, and elsewhere south- 

 westward. It is a remarkable fact, however, that both lithologic- 

 ally and faunally the strata seem to change strongly northwest- 



