Relation of Devonian Faunas of Iowa. — Williams. 231 
are striking illustrations of the value of palseontologic evi- 
dence in determining equivalency of strata. 
In the first paper the author has succeeded in distinguish- 
ing the "yellow sandstone" at Pine creek, which lies above the 
Hamilton limestone, from the "yelloAv sandstone" of Burling- 
ton, which lies at the base of the Burlington group of the lower 
Carboniferous. These two sandstones were called equivalents 
of the "Chemung" by Hall in 1858 and when, in 1861, the 
"Kinderhook group" was defined by Meek and Worthen to in- 
clude the "Goniatite beds" of Rockford, Indiana, and the 
"yellow sandstones" of Burlington, with their equivalents, 
which had been previously referred to the "Chemung," it was 
not strange that a student of the fossils, recognizing the Devon- 
ian relations of the fauna of Pine creek, should conclude that 
the term "Kinderhook," as used by Meek and Worthen, and 
White, should include all of the rocks of the Mississippi val- 
ley that had previously been called "Chemung." 
This mistake I made in an article"On a remarkable fauna at 
the base of the Chemung group in New York." ' 
It is gratifying to learn that professor Calvin has since ob- 
tained palseontologic evidence to convince him that the "yel- 
low sandstone" at Pine creek, Muscatine Co., Iowa, which was 
called "Chemung" and "Kinderhook," is really below the Bur- 
lington "yellow sandstone," which he had regarded as equiv- 
alent, and, therefore, that it is not equivalent to Meek and 
Worthen's "Kinderhook group." 
Without visiting Iowa, and purely from a study of the fos- 
sils and structure of the "Rockford shales" of the northern 
counties of Iowa, I was led to identify their fauna with one 
occuring above the typical Hamilton fauna of the East, as is 
shown in the paper above referred to ; and, although I have 
not yet had an opportunity to examine the stratigraphy, my 
knowledge of the fossils leads me to believe that the fauna of 
the "Rockford shales" follows that of the "yellow sandstone" 
of Muscatine county, described by professor Calvin. 
The fauna of this "yellow sandstone" is probably closely 
related to that of the "calcareo-siliceous sandstone" under- 
the mouth of Pine creek, pp. 7-18. 
Notes on the synonymy, characters, and distribution of Spirifera 
parryana Hall, pp. 19-28. 
» Amer. Jour. Sci., Vol. XXV, pp. 97-104, 1883. 
