432 
the 430 binomial specific names in Massee’s book just 160 are to 
be found in Lister’s. The student who would compare or make 
use of both works must spend much time in more or less fruitless 
attempts at cross-references, for the indexes are defective. 
No charge of adhesion to the laws of priority can be made 
effective against either Massee or Lister, any more than against 
their great predecessor Rostafinski. The indications are that all 
three have believed that variety in names would add a pleasant 
synonymical spice to the study, with the advantage of discourag- 
ing beginners not accustomed to much seasoning of this kind. 
Thus to judge from the past the personal system will not give 
us uniformity, for the recent works differ in nomenclature as much 
or more than the older. A most radical change, however, must 
follow any attempt at an application of the law of priority, for it 
will remove nearly all the names used for the last twenty years, Or 
since the publication of the works of DeBary and Rostafinski. 
Nearly all the Rostafinskian generic names must be replaced by 
others now disused for half a century or longer. If, however, 
these sweeping changes will bring us at once into uniformity with 
all the future, the wisdom of making them is evident—the soonef 
the better. Apparently, however, the application of the rules 
through which uniformity is expected for the higher plants does 
not give the same promise in the case of the Myxomycetes. A 
large number of old generic names exist, and their authors in- 
cluded under them forms now recognized as belonging to several 
different families, for the older writers had absolutely no idea of 
genera as we understand them. The classification in this group 
is by no means settled, and the principle that a genus is a nega 
tive conception merely, and consists of what may be left under a 
generic name after subsequent genera are withdrawn, will bring 
about in the Myxomycetes the result that with changes of view on 
the relative importance of characters, changes in nomenclature 
will be necessary. To illustrate by a simple case, the genus 
Physarum was described by Persoon (1 797) on four species, aS 
follows: 
Physarum columbinum=Lamproderma. 
“eé 
bivalve=Angioridium, 
“ . | —Tilmadoche, ween 
