CONCERNING NOMENCLATURE. 299 



frond." From the groups under this division marked d 

 the one with roundish sori is selected and the division 

 under it, with reniform indusium, shows his plant to be 

 an Aspidium. Had the indusium been hood-shaped it 

 would have been Cystopteris, if star-shaped, Woodsia, and 

 so on. A simple magnifier costing from fifty cents to 

 one dollar will be found exceedingly useful in making out 

 the nature of the indusium and in examining other mi- 

 nute parts of the ferns. 



The majority of our fern genera contain so few species 

 that keys to them would be quite superfluous. For the 

 larger genera, Keys have been given by which the species 

 may be traced, just as the genera are in the large Key. 



Few who get really interested in ferns can resist the 

 temptation to make an herbarium. Upon this point the 

 author's papers on "The Making of an Herbarium " may 

 be consulted with advantage. To the student of ferns 

 the herbarium is indispensable. It gives him material 

 for study at times when it cannot be procured afield, and 

 remains as a permanent record of much that would be 

 lost if merely entrusted to the memory. In collecting 

 for the herbarium or the fern garden, care should be 

 taken not to carry away all of any rare species. No one 

 is held in greater contempt by the true student than the 

 vandal who ruthlessly destroys a station for a rare plant. 

 It is well to remember the old rule " Of a little, take a 

 little, and leave a little." 



