38 Illinois State Lahoratory of JS^atural History. 



By the elevation of railroad stations, the level of the 

 track at the platform is intended. For each town not 

 on the railroad, the location of its post office in the years 

 1891 and 1892 may be understood, and for sections, the 

 elevation of the highest point in the section is given. 



Grateful acknowledgment is here rendered to the offi- 

 cials of the U. S. Government, as above indicated, to offi- 

 cers of the railroad lines of the State, to Dr. J. Lindahl, 

 ex-State Geologist, for many courtesies during the prog- 

 ress of the survey, and to Mr. J. G. Mosier, whose intelli- 

 gent assistance aided me greatly in the collection of the 

 material. 



C. W. ROLFE. 



University of Illinois, 

 April io, 189i. 



