122 NATURAL HISTORY BULLETIN. 



The classification which is employed in the following pages 

 may require some explanation. In general that system of 

 classification is best which most clearly shows the natural 

 relationship of groups and species, and which is at the same 

 time most convenient. 



Lines are not so sharply drawn in the organic world that we 

 may in any larger group express with absolute certainty the 

 relationship which exists between its members, and frequently 

 the attempt to do this in detail leads to a classification which is 

 cumbersome, and which after all from the very nature of the 

 case, neither does nor can give complete satisfaction to 

 him who considers any system of classification merely an ex- 

 pression of relationship, nor can it save altogether from con- 

 fusion the student who would use classification simply as a 

 convenient means of reference, — an instrument which is to 

 facilitate not retard his work. Considerations of reasonable 

 expression of relationship, and of convenience and utility, 

 would seem to dictate an intermediate course. 



The confusion which exists in the nomenclature of tropical 

 Ferns is partially explained by the great variation and inter- 

 gradation of the species, but it is largely due also to the fact 

 that the greater part of the systematic work which has been 

 published was done by those who studied dried specimens 

 only, these often mere fragments, or by those who had oppor- 

 tunities to observe growing plants only in conservatories where 

 many of the species probably will not attain their normal 

 development. In either case there has been needless multi- 

 plication of species based upon insufficient material, though 

 occasionally the other extreme was reached and distinct 

 forms were included under one specific name. 



Probably no satisfactory solution of many of the problems 

 of synonymy can be reached until the student of these inter- 

 esting forms, well-equipped with apparatus and literature, will 

 settle down for a protracted period in the region where they 

 abound, giving his time not only to field-work but also to that 

 close comparative study which is made possible only by years 

 of residence. 



