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. 

 chcll, as follnws: 



Marshall Group, consisting of 



1. Napoleon sandstone 123 ft. 



2. Marshall sandstone if.o ft. 



3. Huron gritstones 1 1^ ft. 



Huron Group, consisting of 



4. Argillaceous shales and flags ^oo ft. 



5. Green arenaceous shales 25 ft. 



6. Black (Genessee) shale 2:^ ft. 



Hamilton Group. 



