8 
BULLETIN OF THE LABORATORIES 
a few inches to several feet in thickness, and corresponding in position 
to with those of Fair Haven and Todd’s Fork, in Ohio — the so-called 
Medina. 
The top of the Upper Silurian of Indiana has also been well de- 
termined. It consists of the highly magnesian rock known as the 
Guelph, in Canada, and the Cedarville, in Ohio. It has been identi- 
fied in Grant, Madison, Delaware, and Randolph counties ( 13th Rep. 
Ind. Geol. Surv.); across the line it occurs again in the north of Preble 
county, Ohio. 
In Ohio the Springfield beds have been identified at Eaton, Preble 
county; and the West Union beds seem to be entirely lacking. The 
Springfield strata are in reality very closely allied to the Cedarville 
strata, and are distinguished mainly by the great abundance of the 
brachiopod, Petamerus oblongus, and by the fact that it usually shows a 
more decided tinge of blue. The blue magnesian rocks immediately 
to the south of the Guelph series already mentioned may safely be re- 
ferred here. 
In Ohio the Eaton beds extend south, reaching to a distance with- 
in four miles of the Clinton exposures at Fair Haven. About two 
miles north of the latter, the intervening portion is seen to contain 
limestone beds, and also some cherty layers, one of which is well 
marked, about nine inches thick, and contains numerous specimens of 
Atrypa 7 'eticularis. Now if the cherty layers here may be considered 
fairly equivalent with the cherty beds usually found beneath the 
W^aldron fossil beds of Indiana, then the Waldron beds may fairly 
be considered the equivalent of the Upper Niagara shales of 
Ohio and perhaps to contain sufficient association with the 
Springfield beds to give its fauna a tinge of the facies of the Guelph. 
The part below the cherty beds in Indiana would then contain the 
materials recognized in Ohio as Clinton, Dayton, and perhaps the 
lower part of the Niagara shale strata. The Clinton has been report- 
ed from various parts of Indiana, but until the paleontological proofs 
for such references are given, it will be impossible to make any use of 
the identifications so far made. 
Paleontological facts also bear out these conclusions. The fauna 
of the Waldron shales has quite a decided relation to the Guelph fos- 
sils. It is not a typical Guelph fauna, but it has a facies approaching 
that of the Guelph and a fair number of species are identical. The 
