Unitep States GEoLocicaL SuRVEY, 
New York, June 4, 1884. 
Sir: I have the honor to transmit herewith the report of Mr. Charles 
D. Walcott on the ‘Paleontology of the Eureka District.” 
The publication of Mr. Walcott’s monograph marks an era in the his- 
tory of the Paleozoic paleontology of the Far West. Heretofore the col- 
lections of fossils obtained have been in most instances small, incomplete, 
and hastily gathered from more or less widely separated localities. If the 
species obtained proved sufficient to determine the geologic horizons for 
the purpose of comparative study, little more was expected. 
Now we possess the results of a careful survey of a district with a rich 
fauna, through 30,000 feet of Paleozoic strata, representing the Cambrian, 
Silurian, Devonian, and Carboniferous rocks. 
Mr. Waleott’s intimate knowledge of the geological and structural 
features of the district lends additional weight to his own special labors. 
I regard his report as the most important contribution yet made to the 
invertebrate paleontology of the Basin Ranges, and of great value in its 
bearings upon the geology of the Cordillera, which under your guidance 
we are gradually working out. 
Very respectfully, your obedient servant, 
ARNOLD HAGUE, 
Geologist in Charge. 
Hon. J. W. PowELt, 
Director United States Geological Survey, Washington, D. C. 
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