14 
BULLETIN OF THE LABORATORIES 
many cases evidence is wanting as to the fact that the stratum referred 
to actually belonged in the same group or formation as those with 
which it was collocated. The question was entirely open as to whether, 
for example, those species figured in the Ohio Palaeontology were dis- 
tributed throughout the series or were characteristic of limited zones. 
Many species have been referred to the Waverly, which all precedents 
show to be true coal-measure forms, while in a few cases Devonian 
species are brought into curious and unexpected relations with such 
species. We are quite in the dark as to whether the coal-measure 
forms are associated in the same actual horizon with Devonian types 
or whether the collocation of faunae is more or less arbitrary or, at 
best, merely a theoretical result of a general survey. 
The Ohio Waverly is the natural arena for the settlement of the 
problem as being the most accessible and the earliest known. These 
rocks were first confidently referred to the position of the Chemung 
of New York, but a more extensive comparison has shown that the 
Waverly is much more closely allied to the carboniferous than was 
first supposed. Prof Alexander Winchell, who has given most atten- 
tion to this series (which he calls Marshall) regards these rocks as the 
equivalent of at least a part of the strata usually referred to the Oris- 
kany. It is our purpose to defer extended discussion of these points 
to the close of this series and our use of the term Waverly is to be 
understood as waiving the matter of terminology, though that name 
has priority, in Ohio at least, and its use in the restricted modern 
sense does not involve any ambiguity. 
To illustrate what has been said of the great importance and 
difficulty of stratigraphical determinations we may allude to the 
condition of our knowledge regarding the equivalent rocks in Michi- 
gan. The serial relations in that state are, according to Prof Win. 
chell, as follnws: 
Marshall Group, consisting of 
1. Napoleon sandstone 123 ft. 
2. Marshall sandstone 160 ft. 
3. Huron gritstones 15 ft. 
Huron Group, consisting of 
4. Argillaceous shales and flags 500 ft. 
5. Green arenaceous shales 25 ft. • 
6. Black (Genessee) shale 25 ft. 
Hamilton Group. 
