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York, and passing the east branch of the Cincinnati axis into the 

 Michigan basin, the paleontological characters of the corresponding 

 beds there seem to be as different, or nearly so, from those of Ohio and 

 New York as they are from each other. Of course the strata cannot 

 be traced continuously from New York to Michigan, yet we feel war- 

 ranted in regarding them as of the age of the Chemung group of New 

 York, and so far as we know no one has questioned it. 



A wide geographical range of species in the Chemung rocks has not 

 heretofore been satisfactorily made out, and the references which have 

 been made of the rocks in the Western States to this group seem to 

 have been based upon their relative position, and the generic value of 

 the fossils which they contained, together with a not unremarkable 

 similarity of lithological characters. 



If it is our desire, as far as possible, to recognize formations over 

 wide areas, which are already well known and named, it appears 

 evident that we must ultimately be confined to the use of generic 

 values and relative position ; but we believe we are not reduced to 

 this necessity as regards the rocks under discussion ; for we are confi- 

 dent that some of the species found at Burlington and other places in 

 the West, of the same geological horizon, are identical with some of 

 those found in the Chemung rocks of Ohio, which rocks can be traced 

 continuously to New York. In the Chemung rocks of Licking Co., 

 Ohio, Prof. Hall has discovered a Goniatite ( G. hyas) which is iden- 

 tical with one of the Rockford species, and Messrs. Meek and Worthen 

 have identified several species in the Rockford beds with some found 

 in the known equivalents of the lower beds at Burlington, in Missouri 

 and Illinois; we have identified several species as common to the 

 lower rocks at Burlington and the Chemung of Ohio. Thus it seems 

 clear that the paleontological connection of these rocks is complete ; 

 and until the intermediate ground between the Mississippi river and 

 New York has been carefully examined in detail, and it shall fully 

 appear that we are wrong in our identification of the species referred 

 to, we deem it inexpedient to use any other name for the rocks from 

 which our fossils are derived, than that adopted by the State geologist 

 of the State in which they are located, and now become a part of its 

 geological nomenclature ; for, notwithstanding their carboniferous 

 character, we think their reference to the Chemung of New York 

 legitimate and proper. 



It is well known that great difference of opinion has existed among 

 geologists as to the proper position in the geological scale of the rocks 

 under discussion. De Verneuil had doubtless good reason for consid- 

 ering a part of the Chemung rocks of Ohio as carboniferous ; and if he 

 had been in possession of facts since ascertained, but only in part 

 published, he might have been, if possible, even more confident ; for 



