DEPARTMENT OF THE INTERIOR, 
Unirep States GEOLoGIcaL SuRVEY, 
Washington, D. C., June 1, 1884. 
Sir: Herewith I have the honor to transmit a report on the inverte- 
brate fossils of the Paleozoic rocks of the Eureka District, Nevada. 
I am greatly indebted to you for the personal interest you have taken 
in the work and generous facilities given me, both in the field and office, in 
carrying on the earlier part of this investigation. 
I am also under many obligations to Hon. J. W. Powell, Director of 
the Geological Survey, for the opportunity afforded me to continue and 
enlarge the work after the completion of the original report. 
Very respectfully, 
CHARLES D. WALCOTT. 
Mr. Arnoutp Hacue, 
Geologist in Charge. 
