IV PEEFA.CE. 



in European herbaria is earnestly commended to those botanists 

 who are not familiar with the method of types or who are opposed 

 to its application. 



Opportunity was given by various curators for the examination of 

 specimens in their charge. Acknowledgment is made, however, to 

 B. Davdon Jackson, Carl A. M. Lindman, P. H. Lecomte, and A. B. 

 Rendle for special courtesies and assistance rendered by them in 

 facilitating the examination of collections in their charge. 



FREDEEICK V. COVILLE, 



( 'urator of the United States National Herbarium. 



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