ON THE EXTINCT YERTEBRATA OF THE EOCENE OF WYOMING, 

 OBSERVED BY THE EXPEDITION OF 1872, WITH NOTES ON 

 THE GEOLOGY. 



PniLADELPiirA, April 29, 1873. 



I send herewith a detailed report of the results of the paleoutological 

 survey of the Green Eiver Tertiary basin, undertaken last summer by 

 myself, under your direction. The report is not complete, but includes 

 the general determination of the vertebrata, with special mon-ograpLs 

 on some of the mammalia. 



The expedition left Fort Bridger July 19, 1872, and followed ^he road 

 to Cottonwood Creek, southeast eighteen miles, whence we made our 

 first excursions into tlie bad lands. After this, our route lay along 

 Cottonwood Creek to Smith's Fork of Green River, tlience along Black's 

 Fork, and thence to Green Eiver City. We then followed Bitter Creek 

 to Black Buttes, and, leaving the line of the Union Pacific Eailroad, 

 traveled south towards the headwaters of the Vermillion. Before reach- 

 ing this point we explored the Mammoth Buttes, which form the water- 

 shed between South Bitter Creek and Vermillion, and examined the 

 bad lands carefully. In reaching this point we crossed a portion of the 

 Cretaceous formation, and I took especial i)ains to determine the rela- 

 tions of the strata at these points. 



We returned from this region, and struck Green Eiver seventeen 

 miles above Green River City. We proceeded northwards to the mouth 

 of Labarge Creek, and, returning a short distance, ascended Fontanelle 

 Creek to near its source in the outlying ranges of the Ham's Fork 

 Mountains. The relation between the lake-deposits and the older strata 

 here claimed special attention. We then descended Ham's Fork to the 

 Union Pacific Eailroad and returned to Fort Bridger. 



Special expeditions were made to the region round Evanston, and to 

 Elko, ISTevada, with gratifying success. 



I leave discussion of the general results until the close of the report. 

 I may premise that we obtained in round numbers one hundred species 

 of vertebrated animals of the Eocene period, of which about sixty were 

 new to science. We added two orders of mammals to those previously 

 represented in this fauna in the United States, viz, the Quadrumana, 

 (monkeys,) and Froboscidia, the latter in several types ot remarkable 

 interest. 



The present synopsis includes only the species of vertebrata collected 

 by the expedition, with one or two exceptions, which* is respectfully 

 submitted. 



EDWAED D. COPE, 

 Paleontologist, United States Geological ISurvey. 



Dr. F. V. Hayden, 



In charge of Geological Survey of the Territories. 



35 G S 



