The Rogers Gap Fauna of Central Kentucky 115 



zons, although very common in the higher zones between Rogers 

 Gap and Sadieville, where Plectatubonites is very common. Heb- 

 crtella latasulcata is another one of the species which occurs oc- 

 casionally at lower levels, but which is common only in the upper 

 zones, in which Plectauibojiitcs is common. The striking feature 

 about this locality 59.1, one mile north of Rogers Gap, is the fact 

 that, for a vertical distance of 33 feet above the basal, coarse- 

 grained limestone, Plcctamhonites is present, but never abundant. 

 It is abundant only at the higher horizons, discussed later. 



Farther northward, at 58.9 miles south of Ludlow, the coarse- 

 grained basal limestone is exposed a short distance below^ track 

 level. Only about two and a half feet are seen, but there may be 

 more layers of the same kind at a lower level. The overlying 

 strata, corresponding to those at 59.1, contain Constellaria ema- 

 ciata, a form with a poorly preserved cardinal margin, w^hich may 

 be an Orthorhynchula, Zygospira recurvirostra, Cyclonema vari- 

 cosuui-cincinnatieiise, and Modiolopsis rogerscnsis. 



At the next cut northward, 58.8 miles south of Ludlow, the 

 basal coarse-grained limestone has thinned out, and the rock most 

 nearly approaching it in horizon presents quite a different litho- 

 logical appearance. Twenty feet farther up there are several layers 

 of coarse-grained limestone, totalling a thickness of six feet ; in 

 these coarse-grained limestones Eridorthis nicklesi and Cyclonema 

 varicosum-cincinnaticnsis occur. The striking feature about this 

 upper coarse-grained limestone horizon, associated with Eridorthis, 

 is the fact that three and a half feet higher Plectambonites is com- 

 mon. Plectanibonitcs is not common over the lower basal, coarse- 

 grained limestone layer. 



The upper coarse-grained limestone containing Eridorthis is 

 exposed again farther northward, at 58.6. Three and a half feet 

 above this limestone Plectambonites is abundant. One foot farther 

 up there is a coarse-grained limestone layer, nine inches thick, 

 also containing Eridorthis. In the overlying thinner bedded strata 

 Plectambonites is abundant, associated with occasional specimens 

 of Strophomena hallie. 



11 



