MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
49 
While the Dayton, Osgood, and Laurel strata of Montgomery, 
Miami, Darke, and Preble counties bear considerable resemblance 
to the corresponding sections in the area immediately southwest 
of Laurel in Indiana, the so-called Osgood of Ohio does not carry 
the typical Osgood fauna of Ripley and Jefferson counties in 
Indiana, and the so-called Laurel of Ohio does not carry the- 
Laurel fauna so well known in the St. Paul and Waldron areas of 
Decatur and Shelby counties of Indiana. 
No equivalent to the Euphemia and Springfield strata is 
known at present in Indiana. The Cedar ville dolomite of Ohio 
carries a fauna much nearer that of the Racine of Wisconsin 
and northern Illinois than that of the Louisville limestone of 
southern Indiana and northern Kentuck^L The upper Niagaran 
strata of the eastern counties of Indiana carry faunas much 
nearer that of the Wabash area of northern Indiana than that 
of the Cedarville of Ohio, or the Louisville of the southern part 
of Indiana. Finally, the upper Laurel fauna of St. Paul has 
its affinities rather in the Racine faunas of Wisconsin and north- 
ern Illinois than in anything known in Ohio. 
In other words, the evidence is accumulating that the Silurian 
strata of Ohio, Indiana, and Kentucky present a much greater 
complex of faunas than would be supposed by the simple alterna- 
tion of limestone and clay zones in the various areas. While 
those unacquainted with the faunas will readily match limestones 
and clays of one area v/ith limestones and clays of another area, 
notwithstanding great differences in faunal content, the paleon- 
tologist is not so ready to follow this procedure. In our present 
state of knowledge of the Niagaran faunas, most of our correla- 
tions are worth very little, and must be considered merely 
tentative. There is a great lack of knowledge of the content 
and geographical range of the various faunas. Until this lack 
is supplied by accurate information, substantial progress is 
impossible. Detailed paleontological work on Silurian strata 
in Ohio, Indiana, and Kentucky has practically ceased, and 
until serious study again is undertaken no vital progress can 
be expected. 
