LIMESTONE MOUNTAIN AND SHERMAN HILL, MICHIGAN 257 



These fossils are few in number but so characteristic that there 

 can be no doubt of the presence of mid-Devonian rocks in or near 

 Limestone Mountain. 



Niagaran (Lockport). — A bed of very siHceous material was 

 found on the south slope of Big Limestone. It could not be 

 traced for any very great distance nor could any satisfactory 

 determination of its position be made. No trace of a similar layer 

 was found in any other outcrop. The fossils collected are: 



Streptelasma spongaxis 

 Zaphrentis stokesi 

 DuncaneUa{?) sp. 

 Clorinda cf. ventricosa 

 Pentamerus sp. 

 Chonchidium decussatum{ ?) 

 Dalmanella cf. elegantula 

 Leperdita aff. cylindrica 

 Loxonema sp. 



Middle to Upper Richmond. — Three fossils were found with the 

 Niagaran material which show the presence of this horizon, but 

 the bed could not be distinguished stratigraphically from the 

 Niagaran. 



Favosites asper 

 Columnaria alveolata 

 Plectorthis whitfieldi 



Upper part of the Lower Richmond {Arnheim). — Near the south- 

 eastern comer of Big Limestone a thin layer of dolomite was 

 found in the bottom of a deep gully. The layer was almost per- 

 pendicular, but as it was in the zone of broken talus we cannot be 

 sure that it was in place. 



Crinoid columnals 

 Coelockma oweni 

 Mitoclema minutum 

 Mesotrypa patella 

 Bythopora striata 

 Rhytichotrema perlamellosa 

 Rhynchotrema capax 

 Conularia formosa 

 Primitia cincinnatiensis 

 Tetradella persulcata var. 



