IX. 
one an idea of how the systematical classification of the species has been un- 
derstood in the course of times; in a certain sense it may be said to give us 
its systematical history and render it possible in a moment to make any con- 
ceivable combination of names with the correct author-citation. 
The nomenclaturic principles, underlying the designation of genera and 
species, will plainly appear from the work itself. I have a clear understanding 
that some peo wont approve of the names chosen, but it is a comfort to 
me that the càse would have been just the same had I followed any other 
principles. I shall only mention here that no name published before 1st edition 
of Linné's Species plantarum 1753 has been included, neither any name pub- 
lished since 31. Dec. 1905. 
Still a remark about the great desirability that authors when naming 
new species should be careful in ascertaining, as for as it is possible, that 
the contemplated name of species has not already been used (even if now 
it has been reduced to a synonym) not only in the genus in question, but 
also in the subgenera of the latter. Forinstance: No Polgpodium should 
be given a name that has been used under Campyloneurum, Goniophlebium, 
Pleopeltis, etc. In exceedingly many instances you never know, if this older 
name may not be adopted by a laterauthor, the form in question represented 
by the name proving to be a good species and accordingly will be referred 
to Polypodium. Hence the necessity of having a new name for the new species. 
This may be easily avoided by consulting ist part of Index and see which genera 
(adopted or not adopted) should be looked over in the list of species (or syno- 
nyms). Another instance: No new species belonging to Polgpodium $ Phego- 
pteris Hk. & Bak. ought to be given a name which formerly has been used 
either under Polypodium, Dryopteris, Nephrodium, Lastrea, Aspidium, Phego- 
pteris, Leptogramma, Goniopferis, etc. This has been my principal nomenclaturic 
point of view, and it has been the cause of a great part of the versions of 
names done. 1f this rule is conscientiously followed in the future, 1] firmly 
believe that the confusion of the pteridological nomenclature will be reduced 
considerably. 
In the first part I have attempted to arrange all the generic synonyms 
under each adopted genus in such a manner as will enable you to find out . 
under which generic name a given group of allied species has been placed. 
The order of the group-names under each subgenus is following the arran- 
gement of the species given in »Die Natürl. Pflanzenfam.- and is of no syste- 
matic value buta guide to the student in the mystery of pteridological nomen- 
clature. — In the enumeration of the species of the larger genera each species 
is prefixed a letter signifying the subgenus — adopted in the first part — to 
which the species is meant to belong. In the case of Trichomanes these 
subgenera are named by different names in the first and second part, the 
names in the first part in my opinion being the best. 
. In the »Catalogue of Literature- I have confined myself to enumerating 
only the works which are quoted in the Index. Several others should be 
included if a complete bibliography of works dealing with ferns, systematically 
or geographically, was to be compiled, but the place did not permit this. 
