43° 
The Ohio Naturalist. 
[Vol. XII, No. 3, 
to give special designations to these divisions; the upper Amheim 
being called the Oregonia division, and the lower Amheim, the 
Sunset division. 
The ease with which the two divisions of the Amheim may be 
traced is due largely to the fact that the Oregonia division includes 
a characteristic fauna which may be identified readily even by a 
beginner in the study of fossils. This fauna includes Dinorthis 
carleyi, Rhynchotrema dentata var., Leptaena richmondensis var., 
and Platystrophia ponderosa. H 
In Ohio and Indiana Dinorthis carleyi recurs in a slightly 
different form at the base of the Blanchester division of the 
Waynesville member; Rhynchotrema dentata is found in the 
Blanchester division of the Waynesville member and near the 
upper part of the Whitewater member; and Leptaena richmonden- 
sis ranges from the Clarksville division of the Waynesville to the 
top of the Whitewater. But none of these fossils is found asso- 
ciated with Platystrophia ponderosa anywhere except in the lower 
part of the Oregonia division of the Arnheim. It is this association 
of fossils which gives them such great value as horizon markers. 
Moreover, if attention be confined to Kentucky, then Dinorthis 
carleyi and Rhynchotrema dentata here occur only in the Oregonia 
division, and within this limited territory they are strictly charac- 
teristic of the upper Amheim. 
TABLE OF SUBDIVISION'S OF CINCINNATIAN STRATA. 
1 
Elkhorn • 
Whitewater 
Saluda 
Richmond ■ 
Laughery ■ 
Liberty 
Waynesville 
Blanchester 
Clarksville 
Fort Ancient 
Arnheim 
Amheim 
Oregonia 
Sunset 
Maysville , 
McMillan • 
Mount Auburn 
Corryville 
Bellevue 
Fairview , 
Fairmount 
Mount Hope 
Eden , 
Eden , 
McMicken 
Southgate 
Economy 
Fulton 
Catheys < 
Catheys /Nicholas 
Cj reendale 
