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PREFACE. VII 



Further changes consist in the withdrawal of the bibliography follow- 

 ing- each .species name, the arrangement of the synon^^mj in chrono- 

 logical order, and the in.sertion of the dates of publication. The 

 names of periodicals have also been substituted in the citations for 

 subtitles, and a number of names which are clearly nomina nuda ha\'e 

 been withdrawn. One new specific name has been changed because it 

 was found to be a homonym. 



The seventh and last paper is "Studies of Tropical American 

 Ferns— No. 1," by William II. Maxon. During the la.st decade the 



National Museum has acquired large collections of Mexican and Cen- 

 tral American plants. These collections are ricli in new material, but 

 evidently they are not sufficiently comprehensive to warrant undertak- 

 ing the publication of a general flora of any one of these countries 

 without furtlicr exploration. In order, however, to make public the 

 scientific results of preliminary studies of the collections a series of 

 papers has been carried on in the Contributions from the National 

 Herbarium, under the title "Studies of Mexican and Central Ameri- 

 can riants," }»y Dr. J. N. Kose, Associate Curator. It is now proposed 

 to begin a sinular series under the title "Studies of Tropical American 

 Ferns," by Mr. William 11. Maxon, Assistant Curator. Altliougli at 

 present this will deal largely with Mexican and Central American col- 

 lections, it will include also descriptions of new and noteworthy West 

 Indian species. South American forms will l^e considered al«o, as cir- 

 cumstances may require. 



FrKDKKICK V. COVILLE, 



Cumior <>fl]»e I'olted States National ILrhatiuui. 





