225 Devonian of Southern Indiana 97 



Feet. 



Corniferous limestone. — Upper Helderberg group 22 



Utica limestone. — Niagara group 30 



Madison limestone. — Cincinnati group 207 



Magnesian limestone. — Clinton group 30 



It will be noted that the Rockford limestone, from which the 

 typical Kinderhook fauna was described, is entirely omitted from 

 the above sedlion. 



No important additions have been made to the literature rela- 

 tive to the geological equivalents of the Rockford limestone and 

 the shales and sandstones above them in Indiana since the appear- 

 ance of Winchell's paper in 1870. A number of new fossils have 

 been described from the sandstones and shales of the Knobs by 

 Hall and Clark and Miller and Gurley. In referring a new spe- 

 cies to the Knobstones group Miller and Gurley explain that it 

 "means the Keokuk group and the Waverly, where the two are 

 not separable and the fossils are generally casts."* 



Hall and Clarkf, in referring to the age of the "Knobstone 

 group," state that "the lowest member has generally been re- 

 garded as of the age of the Waverly and the upper member 

 equivalent to the Keokuk." 



Quite recently Mr. Millerij: has attempted to prove by strati- 

 graphic evidence that the Waverly of Ohio and eastern Kentucky 

 formerly extended across the Silurian area and were continuous 

 with the Knobstone and superior formations in Indiana and Ken- 

 tucky west of the Cincinnati geanticline. 



*Bull. 111. Surv., No. 12, p. 50. 



tPal. N. Y., vol. 8, pt. I, p. 225, 



JAm. Geo!., August '98. / y \ i1 , ho,'^ 



