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they are generally inclined to admit that the highest portions may beEocene .

After a careful study of plants collected by Dr. Hayden in the UpperMissouri Region, Dr. Newberry referred the Fort Union Group, as thereexhibited, to the Miocene . This conclusion was based upon the close re-semblance of this flora to the so-called Miocene flora of Greenland and itsintimate relation to the Miocene flora of Europe . Dr. Newberry stillholds this opinion respecting the Upper Missouri Region, though he showssome inclination to dispute the assertion, that the southern portion is asrecent as the Eocene . The stratigraphical evidence, however, is so strongto prove the identity of the group throughout the Rocky Mountain Re-gion , that all parts of the area must belong to the same horizon. If onepart is Miocene the other is Miocene also.

Mr. Lesquereux has published several elaborate and very able papersupon the flora of this group. Though it has close affinity to the Miocene flora of Europe, he does not regard it as Miocene throughout, but dividesthe series containing it into Upper and Lower Eocene, the former repre-sented at Carbon, Evanston , and Sage Greek, and the latter at BatonMountains, Golden, Black Butte, Spring Canon, and Fort Union. As awhole, he regards this vegetation as Oligocene . Above the LigniticGroup he finds the Miocene at Green River, Elko Station, South and Mid-dle Parks.

Dr. Hayden has long halted between two opinions. He looks upon theCoalville and Bear River sections as Ci’etaceous beyond doubt, but con-cerning the rest of the Great Lignite Group he is by no means so de-cided. Sometimes he speaks of the Lignite Tertiary, at others he seemsto regard the group as partly Cretaceous and partly Tertiary , while forthe most part in his more reoent publications he is disposed to regardthe whole as, in great measure, beds of transition. From the beginninghis inclination has been to favor the Tertiary hypothesis. Under suchcircumstances one cannot fail to admire the frankness with which all thefacts are given in Dr. Haydeir’s reports, many of them bearing dircetlyagainst the deductions previously published by the Doctor himself. Judg-ing from his readiness to receive tlnj truth oven at the expense of discard-ing cherished opinions, there is every reason to hope that before very longDr. Hayden will be one of the most energetic expounders of the doctrinethat the Lignitic Gi'oup is Cretaceous .

Mr. Meek refers the Coalville and Bear River areas as well as a portionof the Bitter Creek Series to the Cretaceous but thinks the upper portionof the Bitter Creek section may be Tertiary. He is quite positive thatthe Black Butte portion of the section is Ci’etaceous; but this lies far upin the series.

Prof. Cope is very positive respecting the Cretaceous age of the BlackButte section, because Agathaumus sylvestris occurs there. Prof. Marshis equally positive regarding some other localities. Dr. Leconte, Mr.Arnold Hague, and myself have referred the Colorado beds to the Cre-taceous .