IM.6S 



STATE OF ILLINOIS 



DWIGHT H. GREEN, Governor 



DEPARTMENT OF REGISTRATION AND EDUCATION 



FRANK G. THOMPSON. Director 



DIVISION OF THE 



STATE GEOLOGICAL SURVEY 



M. M. LEIGHTON. Chief 

 URBANA 



REPORT OF INVESTIGATIONS— NO. 83 



OCCURRENCE AND STRATIGRAPHIC DISTRIBUTION OF 

 PALEOZOIC OSTRACODES 



CHALMER L. COOPER 



Reprinted from the Journal of Paleontology, 

 Vol. 16, No. 6, November, 1942 



PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS 



URBANA, ILLINOIS 

 1942 



