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 Ellisburg, in 
Casey county. At several localities, among these the one about 
a mile east of Harveyton, in Casey county, the globular brvozoan 
occurs 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 are found about 16 to IS 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 Corryville. In the area between 
Hankla, in Boyle county, and the locality southwest of Stanford, 
within which Leptaena richmondensis and Rhynchotrema dentata 
are unknown, these dove colored limetsones appear to lie nearer the 
lower Prasopora or globular brvozoan 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 
ponder osa. 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 Plalystrophia 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 Plalystrophia 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. 
