Bui. 42, Bureau of Plant Industry, U. S. Dept. of Agriculture. 



Plate I. 



< 



rr 



HI 



0- 



< 



a. 



w 



LLl 

 Z 

 < 

 Q_ 

 < 

 —} 



HI 



I 



H 



< 



h- 

 < 



3 

 U) 



r- 



I 

 h 



Q 

 UJ 



a: 

 u 

 > 



O 



o 



LU 

 D 



I 

 < 



