212 The American Geologist. October, 1002. 
thereto written to Dr. Stevenson under date of Xov. 8th, 1870. 
The only commentary upon this letter which seems necessary 
is that the beds in question do not come so low in the Coal 
Measures as Mr. Meek supposed, so that instead of coming- 
1000 to 1500 feet below the Nebraska horizon holdino^ the 
same fossils, they probably come at about the same s^eological 
level, since marine conditions terminated entirely in the Appal- 
achian province with the deposition of the Crinoidal (Ames.) 
Hmestone and its accompanying shales. The fauna thereafter 
was of fresh or brackish water type, and at a few hundred feet 
(650) higher, typical Permian plants make their appearance 
in the roof shales of the \\'aynesburg coal. I have arranged 
the fos>ils into two lists instead of the one as given by Mr. 
]\Ieek. otherwisa the following- is an exact copy from the pub- 
lication in question, pp. 67-71. 
"The specimens sent from the lo-.ver Coal Measures are nearly 
all forms common in the coal series of Indiana, Illinois, Missouri, 
Kansas, Nebraska, etc., though few of them have before been found 
so far eastward. In some of the states mentioned, nearlj^ all of these 
species range through the whole of the Coal Measures. Some of 
them, however, are locally more restricted. This great range of the 
species of invertebrate remains in the Coal Measures of the western 
states has long since satisfied me that these fossils cannot generally 
be relied upon as a means of identifying particular beds or horizons 
in our Coal Measures throughout wide areas ; though particular 
groupings of species may sometimes serve as guides in this respect, 
within limited areas. The Coal Measure forms, however,, enable us 
at once to distinguish beds of that age from any of the lower Carlioni- 
ferous or older rocks. 
The great length of time through which most of these fossils must 
have continued to live, will be better understood when it is stated 
that nearly all of the species enumerated in this list from the lower 
Coal Measures of West Virginia, also occur even in the upper Coal 
Measure beds in Nebraska, referred by professors Marcou and Geinitz 
to the Permian or so-called Dyas- Indeed the collections from these 
two widely separated localities and horizons, contain so many of the 
same species, that if shown to almost any geologist unacquainted with 
the range of species in our Coal Measures, he would scarcely hesitate 
to adopt the conclusion that they came from exactly the same horizon 
in the series. Yet from what is known of the geology of your region, 
and that of the states farther west, it is probable that the beds from 
which your collections were obtained, hold a position from 1,000 to 1,500 
feet or more below those alluded to in Nebraska. 
From such facts as this, it would seem that although there were 
many elevations and depressions, as well as other consequent changes, 
