Strophomena and Other Fossils 
19 
and Stanford, the lower part of the Arnheim is characterized by 
an entirely unfossiliferous shaly rock overlaid by a thinner sec- 
tion of dove-colored limestones, and the latter by the richly fos- 
siliferous strata forming the upper part of the Arnheim. In 
central Kentucky, the Arnheim fauna, overlying the argillaceous 
Sunset division, is strikingly different from the underlying fauna 
of the AIcMillan, while northward, in Ohio and Indiana, the lower 
Arnheim fauna bridges the gap between the upper Arnheim and 
the Mount Auburn. 
The stretch of territory between Boyle county, in central Ken- 
tucky, and Adams county, in Ohio, was an important one in the 
distribution of faunas, especially during the deposition of the Eden 
and Maysville. There is abundant evidence that during this 
time there was free access from the seas southwest of central 
Kentucky to those northeast of this area, across the region now 
traversed by the Cincinnati geanticline. Frequently, there is a 
greater similarity of faunas for many miles from Boyle county 
northeastward toward Adams county than for a much shorter 
distance northwest^vard from this line. This is true especially 
during the deposition of the lower and upper part of the middle 
Eden, and also of the Mount Hope and Fairmount. It is illus- 
trated by the early introduction of Strophomena maysvillensis 
along this line, during the Mount Hope, and by the distribution 
of Orthorhynchula linneyi, Escharopora hilli, and Cyrtoceras val- 
landinghami during the later part of the Fairmount. The dis- 
tribution of the Rogers Gap fauna, at the base of the Eden sec- 
tion as exposed in central Kentucky, is chiefly along this channel. 
Even the typical Mount Auburn fauna, extending northward 
to Cincinnati and Lebanon, finds a greater extension in Clermont, 
Brown, and Adams counties in Ohio, and in Lewis, Fleming and 
Bath counties in Kentucky, than in the western parts of Hamil- 
ton and Butler counties, in Ohio, or in any part of Indiana. 
The channel across the region later occupied by the Cincinnati 
geanticline, by way of Casey, Boyle, Lincoln and Garrard counties, 
was open also during the deposition of the upper part of the Arn- 
heim, as is attested by the distribution of Platystrophia ponder osa, 
Rhynchotrema dentata, and to a certain extent by the distribu- 
tion of Leptaena richmondensis during this period. It must have 
been open also for a brief period at the close of the Waynesville 
or the beginning of the Liberty, while the Beatricea and coral 
