D PKEFACE. 



upon which this Department continues to receive a large amount of 

 correspondence of a character which it has been very difficult to treat 

 satisfactorily by letter. 



A large proportion of the notes and illustrations used in the present 

 paper were secured in the Soconusco district of Southern Mexico on 

 the estate of the La Zacualpa Rubber Plantation Company, through 

 whose hospitality and numerous courtesies the work of Mr. Cook was 

 greatly facilitated. 



Frederick V. Coville, 



Botanist. 

 Office of Botanical Investigations 



and Experiments, 



Washington^ D. C, May 18, 1903. 



