6 NORTH AMERICAN GEOLOGY. [bull. 127. 



2. Subject index references. — These are geographic, stratigraphic, and 

 miscellaneous geologic headings, under which are listed condensed titles 

 of the papers, and the author's name for cross reference to the principal 

 entry. The subarrangement is chronologic. A key to these references 

 is given on pages 7-10. A few general text-books of geology and very 

 general papers have not been indexed. 



I am indebted to the catalogue by Prime, the lists of maps by Jules 

 Marcou and J. B. Marcou,i lists of papers on the Lake Superior copper 

 region by J. D. Whitney,^ abibliography of Texas, Arkansas, Louisiana, 

 etc., by J. B. Marcou (in manuscript), and to many gentlemen for infor- 

 mation or advice. I am also indebted for special courtesies to the 

 librarians of the Academy of Natural Sciences at Philadelphia, the 

 New York Academy of Sciences, the Boston Society of Natural History, 

 the Astor Library of New York, and the Boston Public Library. 



Additional references or information for a supplement to this cata- 

 logue will be gratefully received by the author, care of the United 

 States Geological Survey, Washington, D. C, TJ. S. A. 



1 BiiU. XJ. S. Geol. Survey No. 7, 1884. 



^Bull. Mus. Comp. Zool.Harvard College, vol. 7, 1884. 



