Bui. 607, U. S. Dept. of Agriculture. 



Plate IV. 



ft] 





CM 



DC 

 < 



"■t 



h 



0. 



UJ 





CO 



< 



u 



HI 



I 



_i 



CO 



< 



< 



h 



O 





Z CM 



o . 



O' 



6 < 



LU Q 



_ LU 



SO 



li 



UJ O 



