112 



IOWA ACADEMY OF SCIENCE Vol. XXVI, 191U 



uS oi 



. . - H 3 ^ 



a e a d u 



U o o o +3 a> 



•H oj -P p^c^ 



nj ca m hO 



cd a d 4» <« 



a O 3 ,— I ,— I m 



O O +J H 



0) ID U .H 



•^ o o +> 



O 0) O, O 



©H a a 



A O QJ <1> -H -H O 



to cq o w fM P< S 



X! jh a 



D. ft O 

 <1> (B ^1 



a a -p 



to 



