Jan., 1912.] The Arnheim Formation. 437 



Rileys, in Marion county, and thence southward to Rush Branch 

 and eastward to Gravel Switch in Marion county, and EUisburg, in 

 Casey county. At several localities, among these the one about 

 a mile east of Harveyton, in Casey county, the globular bryozoan 

 occtu"s apparently immediately above the horizon containing 

 Leptaena richmondensis and Rhynchotrema dentata. 



At most of the localities in Marion, Boyle, and Casey counties, 

 at which Leptaena richmondensis and Rhynchotrema dentata occur, 

 the latter arc found about IG to 18 feet below the top of the upper 

 horizon at which the globular bryozoans, associated with the 

 argillaceous nodules occur. Below the Leptaena horizon, within 

 a moderate distance, dove colored limestones are found. Near 

 Lebanon, these dove colored limestones occur sufficiently far 

 below the Leptaena horizon to suggest their equivalence to strata 

 elsewhere assigned to the upper Corryvillc. In the area between 

 Hankla, in Boyle county, and the locality southwest of vStanford, 

 within which Leptaena richmondensis and Rhynchotrema dentata 

 are unknown, these dove colored limetsones appear to lie nearer the 

 lower Prasopora or globular bryozoan horizon, suggesting a thin- 

 ning of the lower Arnheim and the absence of the Mount Auburn 

 along this axial region of the Cincinnati geanticline. 



4. Western Kentucky, from Nelson to Trimble Counties. 



Between Lebanon and Cox Creek, seven miles north of Bards- 

 town, a total distance of 25 miles, the Arnheim horizon has not 

 been studied. North of Cox Creek, on the pike to Mount Wash- 

 ington and Louisville, Leptaena is associated with Plastytrophia 

 ponderosa. Seven miles farther northward, in the southwestern 

 corner of Spencer county, between High Grove and Smithvillle 

 Leptaena richmondensis and Rhynchotrema dentata occur in the 

 Arnheim member. The exposures here are so evidently related 

 lithologically to those near Mount Washington, in Bullitt county, 

 about five miles farther, toward the northwest, that they will be 

 discussed in the same relation. 



Southwest of Mount Washington, along the pike to Smithville 

 and Bardstown, the following section is exposed: 



Argillaceous limestone with Platystrophia ponderosa and Con- 



stellaria polystomella 2 ft. 8 in. 



Hard fossiliferous limestone forming a small fall near the home 



of F. C. Porter, where a fence crosses the creek 2 ft. 6 in. 



Richly fossiliferous argillaceous rock with Platystrophia pon- 

 derosa a foot and a half from the top and with Leptaena 

 richmondensis near the base , 5 ft. 4 in. 



Argillaceous rock and thin limestone, richly fossiliferous, with 

 Leptaena richmondensis at various intervals. Platystrophia 

 cypha-conradi occurs rather abundantly. Rhynchotrema 

 dentata is present at the base, on the eastern side of the 

 creek, where a wagon road crosses the creek near the level, 

 485 feet above sea 14 ft. 



