THE PLA^T WORLD. 55 



beginning with the ferns. An alphaV)etical list is then made, in which 

 the name of each family is followed by its number in the sequence. A 

 glance at this list will at once tell us where to look for the required 

 family. Having found this, we must have another index, for just as 

 the families follow a sequence of relationship, so do genera and 

 species. By arranging and numbering the genera in se(|uence and 

 making a list similar to the first, the difiiculties in findino; the genera 

 are overcome. The species must still be disposed of. In small genera 

 we may be able to get along without indexes but with the large genera 

 which often contain more than a hundred species it is l)etter to arrange 

 the species in their natural sequence, in tliis following the latest mono- 

 graphs of the genera, and providing an alphabetical index also. 



For locating the families and genera in the cases, several devices 

 are employed. In some herbariums a piece of pasteboard the size of 

 the mounting sheet with a smaller piece of the same width hinged to one 

 of its ends is used. The large piece is laid in the pigeon hole at the 

 beginning of a family and the smaller piece, hanging down in front, 

 has the family and list of genera which it contains, printed upon it. 

 This, however, is a downright nuisance, for the hanging cardboard is 

 always in the way. Another way is to label the pigeon holes by 

 printed slips which are held in place by a contrivance fastened to the 

 partitions, but this is objectionable because there is then no place for 

 an index and because the labels have to be changed every time there is 

 an addition of new material. Perhaps the best way yet devised, is to 

 make use of a piece of light wood the size of the mounting sheet and 

 about three-eighths of an inch thick. This is laid in the pigeon hole 

 at the beginning of each family. On the visible end is printed the 

 name of the family and its num])er. The upper surface of such a 

 marker gives ample room for a catalogue of all the genera in the 

 family, if not, the other side may be used also. This too may be 

 recommended for use as a marker for the laroer' oenera, in which case 

 the list of species may be })rinted upon it. Such a list is always in 

 position for consulting. 



In all large herbariums, there is suj)i)osed to be a species cover 

 for each species. This is made of a medium grade of manila paper 

 cut to a size of 16f by '2(! inches and folded once. In this the sheets of 

 mounted specimens fit like leaves in a book. At the beginning of each 

 genus a slightly heavier cover of the same size and material, called a 

 genus cover, should be placed. This is to contain species that are not 



