INTRODUCTION. 



I .shall begin my report of this year by a more detailed review of the 

 ■essential facts and data which, furnished essentially by vegetable 

 paleontology, have forced my conclusions on the age and the geological 

 distribution of the Lignitic formations of the "West. 



There is always some uncertainty in the reference of fossil si)ecies to 

 peculiar geological stations, when the paleontologist is called to describe 

 them and judge of their geological relations. without having himself 

 examined the localities wherefrom the materials have been derived j 

 this on account of a casual mixing up of specimens, and also because 

 the more characteristic' species, which are sometimes of rare occurrence, 

 escape the eye of those who, unacquainted with fossils, collect speci- 

 mens at random, and wherever they find them, for the examination of a 

 specialist. For this reason I have to base my cla*ssiflcation on the 

 localities which I have visited myself, and on those which, either from 

 stratigraphical evidence or by a close analogy in the characters of their 

 fossil remains, are ascertained as synchronous. 



1st. I refer to Eocene (Lower American Eocene,) all the coal-strata of 

 the Eaton Mountains ; those of the Caiion City coal-basin ; those of 

 Colorado Springs, where a coal-bed, theGehrung's, is opened and worked; 

 those of the whole basin of Central and North Colorado, extending 

 from Platte Eiver or from the Pinery divide to south of Cheyenne, in- 

 cluding Golden, Marshall, Bowlder Valley, Sand Creek, &c., and, in 

 Wyoming, the Black Butte, the Hallville, and the Eock Spring coal, By 

 analogy of geological characters, compounds, and succession of strata, 

 as indicated by Hayden, Leconte, and others, and also by the presence 

 of species of fossil plants, which I consider as leading plants of the group, 

 I refer to the same Eocene formation the Lignitic beds of l^ew Mexico as 

 far south, at least, as the Placiere anthracite coal ; in Wyoming, those 

 of Bear Eiver; and in Utah, those of Coalville, as described by Professor 

 Meek in the former report of Dr. Hayden, (1872, p. 435.) From its fossil 

 plants, the coal of Nanaimo, Vancouver Island, is referable to this 

 section. 



2d. I consider as American Upper Eocene (or Lower Miocene, the coal- 

 strata of Evanston, and from identity of the characters of the flora, as 

 seen from the specimens communicated to me, those of six miles above 

 Spring Caiion, near Fort Ellis ; of the locality marked near Yellowstone 

 Lake, among basaltic rock ; of Troublesome Creek, Mount Brosse, and 

 Elk Creek, Colorado. The specimens from Bellingham Bay, Washington 

 Territory, refer this locality to the sami^ horizon. 



3d. To the Middle Miocene I refer the coal-basin of Carbon, and from 

 the identity of vegetable remains the Washakie group, Medicine Bow, 

 Point of Eocks, and Eock Creek. 



4th. To tjhe Upper Miocene belongs the Green Eiver .group of Wyo- 

 ming ; the coal of Elko Station, Nevad'a ; the leaf-bearing strata of 

 South Park, near Florisant and CasteRo Eanch ; of Middle Park, and 

 of Barren's Spring. 



The localities where only a few specimens of undeterminate relation 

 have been obtained, and which are not nailed in this connection, are of 

 little importance. They may become positively identified with one of 

 these stages of the Tertiary, and for this reason, in.,o'rder that the means 

 •of comparison may be more easily recognized, I propose to modify the 



