114 POTTSVTLLE FAUNA OF OHIO 



Summary 



In conclusion, the Upper Mercer deposit or the fourth member in 

 the series of marine fossiliferous limestones of Pennsylvanian age, is 

 composed of dark blue limestone which closely resembles the Lower 

 Mercer both in lithologic character, fossil content, and composition, 

 and also of dark to black flint which to a large extent replaces the lime- 

 stone in the central counties of the outcrop. The limestone phase is 

 best developed in the northeastern part of the State including Stark 

 and Mahoning counties, where it reaches a thickness of 3J feet and is 

 equally as fossiliferous and persistent as the Lower Mercer limestone. 

 It is also represented by a flinty limestone in Hocking and Vinton 

 counties, while at various other localities in the southern counties it is 

 generally wanting or where present measures only a few inches in thick- 

 ness. In the central counties, including Perry, Muskingum, and 

 Coshocton, the stratum measures 1 to 15 feet in thickness and is 

 composed to a large extent of flint although limestone may be present 

 with the flint. In southern Ohio the horizon is marked by very per- 

 sistent iron ore with an average thickness of 1 to 1J feet, which lies 

 directly over the limestone where the latter is present. The Upper 

 Mercer limestone is as a rule sparingly fossiliferous, while the flint and 

 ore contain a still more meager fauna, but of the same type as the lime- 

 stone. 



A complete list of fossils from the Upper Mercer member follows: 



Plantae 



Textularia sp. 



Nodosaria sp. 



Fusulina secalica (Say) 



Girtyina ventricosa (Meek and Hayden) 



Lophophyllum profundum (Milne-Edwards and Haime) 

 Crinoid segments and plates 

 Archaeocidaris spines 



Fenestellids undetermined 

 Fenestella limbata Foerste 

 Fenestella shumardi Prout ? 

 Fenestella sp. 

 Pinnatopora sp. 

 Septopora biserialis (Swallow) 

 Septopora biserialis var. gracilis (Meek) 

 Rhombopora lepidodendroidea Meek 

 Cystodictya carbonaria (Meek) 

 Prismopora sereata (Meek) 



Lingula carbonaria Shumard 

 Orbiculoidea meekana (Whitfield) 



