434 
The Ohio Naturalist. 
[Vol. XII, No. 3, 
Stromatocerium occurs also four and a half miles south of Paint 
Lick, or 15 miles southwest of Richmond. Here it occurs about 
8 feet above the base of the Oregonia division. The richly fos- 
siliferous part, containing Platystrophia ponder osa and Leptaena 
richmondensis, forms the lower five and a half feet of this division. 
The top of the lower Arnheim consists of fossiliferous dove colored 
limestone, 5 feet thick, representing the fine grained limestone 
layers containing gasteropods, as seen at Cobb Ferry, College Hill, 
and at the mouth of Red river. Below the dove colored limestone, 
the characteristic shale bed of the lower Arnheim, 13 feet thick, 
is found. 
The unfossiliferous shaly layers, characteristic of the lower or 
Sunset division of the Arnheim, may be traced with confidence as 
far west as Stanford. At three localities along the southwestern 
border of Garrard county, the thickness of the shaly layers varies 
from 16 to 17 feet, and that of the overlying dove colored lime- 
stones, at the top of the lower Arnheim, from four to five and a 
half feet. These localities are : half a mile east of the northern end 
of Preachersville ; three miles southeast of Lancaster, a few hun- 
dred yards west of the pike, along Gilbert creek; and two and a 
half miles southwest of Lancaster, west of the pike to Stanford. 
Farther westward, apparently, the shaly part of the lower Arnheim 
thins rapidly. Two miles northeast of Stanford, and also two and 
three-quarter miles north of Stanford, along the road to Lancaster, 
the thickness of the shaly section is reduced to 7 feet, the overlying 
dove-colored limestone, at the top of the lower Arnheim, measur- 
ing three and five feet respectively. 
The territory between Stanford and the mouth of Red river 
may be regarded as representing a distinct phase of the Arnheim 
sedimentation. Within this territory the lower Arnheim is 
characterized by an unfossiliferous shaly rock overlaid by a thinner 
section of dove colored limestones. The basal part of the upper 
Arnheim division contains Leptaena richmondensis and Rhyncho- 
trema dentata, the latter at a slightly higher elevation whenever a 
difference in elevation is noted. The overlying part of the upper 
Arnheim section usually is richly fossiliferous, and contains among 
other fossils rather numerous specimens of Platystrophia ponderosa. 
At the top of the Arnheim section there is a layer of light colored 
clay, one or two feet thick, frequently containing numerous 
specimens of bryozoans. This clay layer has been assumed to 
form the base of the Waynesville bed, but it may be necessary to 
revise this classification when the fauna is better known. It is 
probable that most of these features may be detected as far north 
as Howards Mill, in the eastern part of Montgomery county. 
The territory from Montgomery county to Mason county, 
already described, includes another phase of Arnheim sedimenta- 
tion. Here the lower Arnheim consists of a rather uniform 
