PREFACE. 
In the present paper, the sixth of the series, Mr. Henry Pittier puts 
on record further results of his Colombian and Central American 
botanical studies. All the species treated are trees or shrubs, and most 
of them are here described for the first time. One of the new species, 
Mimusops darienensis, is the tree which yields the Panama “ balata” 
or gutta-percha, a very important commercial product. Hitherto this 
tree has been confused with another species of Mimusops, from British 
Guiana. 
FREDERICK V. CovILLe, 
Curator of the United States National Herbarium. 
TI 
