FIRST SERIES NO. 11 



OCTOBER. 1917 



UNIVERSITY OF IOWA 

 MONOGRAPHS 



BULLETINS FROM THE LABORATORIES 

 OF NATURAL HISTORY 



VOLUME VII NUMBER / ^ 



Collected Studies and Reports 



PUBLISHED BY THE WNIVERSITY, IOWA CITY 



ISSUED MONTHLY THROUGHOUT THE YEAR. ENTERED AT THE POST OFFICE AT 

 IOWA CITY, IOWA. AS SECOND-CLASS MAIL jVlATTER 



