26 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



stated, in the first place, that Emmons evidently regarded it as Cretaceous, as 

 may be seen from his remarks in Mr. King's report, published in 1870, while 

 Dr. Hayden favored the conclusion that it is a marine Tertiary group, or a 

 transition series betvi^een the Tertiary and the Cretaceous, in his reports of 

 that and the following year." 



"The only fossils I had ever seen from this formation previous to visiting 

 the region during the past summer were two species of Ostrea and one of 

 A)iomia from Point of Rocks, and two shells, one or possibly both related to 

 Corhicula, from Hallville. Those from Point of Rocks I referred to the Creta- 

 ceous, placing them in the Cretaceous list in Dr. Hayden's report, 1871. 

 This I did mainly because there were among them no fresh-water or strictly 

 brackish-water types, while up to this time we knew of no Tertiary of ex- 

 clusively marine origin in all this internal region of the continent. I was 

 also in part influenced in making this reference by the similarity of one of 

 the Oysters to a Cretaceous species found in California, while the Anomia 

 likewise closely resembled a Texas Cretaceous shell described by Roemer 

 under the name of Ostrea anomiceformis, which certainly seems not to be a 

 true Oyster. The two shells from Hallville, however, I referred to the Eo- 

 cene, not only because they were closely allied to Eocene brackish-water 

 forms from the Paris Basin (peculiar depressed and elongated form of Cor- 

 bicula), but because I was not aware at the time that the Hallville mines 

 occur in the same formation as the Point of Rocks beds, nor even within 

 fifty to seventy-five miles of the same locality. 



"On visiting these localities, however, last summer, I was somewhat sur- 

 prised to find that the Hallville mines are only some seven or eight miles from 

 Point of Rocks, and belong to the same geological formation. A careful 

 examination, also, soon rendered it evident that all of the rocks for sixteen 

 hundred to eighteen hundred feet or more above the Hallville coal beds, up 

 to and including the stratum in which we found the large reptilian remains 

 at Black Buttes, and for even a little greater thickness below the Hallville 

 horizon, certainly belong to the same group or series of strata, and that fresh- 

 and brackish-water types of fossils occur along with salt-water forms at all 

 horizons wherever we found any organic remains throughout this whole 

 series." 



From this flict, Prof Meek was induced to modify his views, and to con- 

 sider the whole series Cretaceous, by some reason which I do not consider as 



