43 2 
The Ohio Naturalist. 
[Vol. XII, No. 3, 
South of Maysville, however, the lithologic differences between 
the upper and lower Arnheim become even more striking. 
About a third of a mile southwest of Sunset, and two miles 
southwest of Hillsboro, in Fleming county, Kentucky, the Sunset 
division, 13 feet thick, consists of a rather uniform section of 
dense, argillaceous, dark blue limestone, nearly unfossiliferous, 
but containing a few specimens of Platystrophia ponder osa about 
three feet below the top. The overlying Oregonia division contains 
considerable clay, interbedded with fossiliferous limestone which 
has weathered into a limestone rubble. 
East of Wyoming, four miles south of Sunset, the lower Am- 
heim, 15 feet thick, presents the same lithological appearance as 
at Sunset. Occasional specimens of Platystrophia ponderosa 
occur at different elevations. A variety of Leptaena richmondensis 
and one of Rhynchotrema dentata are found at the base of the 
Oregonia division. 
The dark blue argillaceous limestone phase of the lower or 
Sunset division of the Arnheim bed may be traced as far south as 
Howards Mill, five miles east of Mount Sterling, Kentucky. East 
of the mill, it is 18 feet thick and contains occasional specimens of 
Platystrophia ponderosa near the base. The overlying Oregonia 
division consists of rubble limestone with numerous bryozoans. 
South of Howards Mill, the lower division of the Arnheim 
becomes more shaly and weathers into a more sandy rock. Platys- 
trophia ponderosa disappears, southward, from the lower division 
but becomes more abundant in the upper division. Half a mile 
southwest of Howards Mill, the lower division, 14 feet thick, 
consists of rather unfossiliferous, brown, shaly, sandy rock, 
weathering to a sandy clay. In the overlying Oregonia division, 
Rhynchotrema dentata is rather rare and Ileterospongia subramosa 
occurs. Platystrophia ponderosa is abundant. 
At the mouth of the Red river, at Merritts Ferry, Platystrophia 
ponderosa is abundant in the lower 8 feet of the Oregonia division. 
Leptaena richmondensis is found at the base, and Rhynchotrema 
dentata occurs one foot above the base of this division. The top 
of the lower division is formed by a very fine grained, bluish 
limestone, containing small gasteropods, chiefly Lophospira. 
Traces of this limestone are found as far northward as Indian 
Fields, eight miles northeast of Merritts Ferry. 
The same limestone, blue, fine grained, and containing gas- 
teropods, occurs one mile east of College Hill, four miles south of 
Merritts Ferry. Here the upper layer of limestone is one foot 
thick, the lower layer is a foot and a half thick, and the underlying 
shaly part of the lower Arnheim has a thickness of 11 feet. In the 
Oregonia division, Platystrophia ponderosa is confined to a section 
.about two feet thick, two feet above the base of the division. 
