The Philippine Journal of Science, C. Botany. 
Vol. X, No. 2, March, 1915. 
REVIEW 
Christensen, Carl. Index Filicum. Supplementum 1906-1912. Hafniae: 
H. Hagerup. Pp. 1-132. 
Christensen has published a Supplement to his invaluable In- 
dex Filicum, covering the ferns described, and the literature 
dealing with the names of ferns, during the seven years from 
1906 to 1912. During this period, there have been proposed 
33 new genera and subgenera, and 2,611 specific names. Of 
the species, Christensen regards 1,644 as entitled to recog- 
nition. The total number of species of ferns recognized at the 
end of 1912 is 7,411. Publication on ferns has been so active 
since the Index Filicum was printed that it had already become 
very difficult for writers on the subject to be familiar with the 
whole of it, and the Supplement is therefore second only to the 
Index itself in its value as a guide to those who would describe 
plants in this group. It appears that the publication of the 
supplement was made possible by the financial aid of Prince 
Roland Bonaparte, to whom, therefore, the thanks of all students 
of ferns are due. 
The supplement is divided into two parts: First, the supple- 
ment proper, containing all new names and a few older ones 
overlooked in the preparation of the Index; and, second, the 
Corrigenda, containing corrections and additional synonyms to 
species adopted in the original Index. This arrangement is 
inconvenient and must have involved a large amount of addi- 
tional work on the author’s part, and appreciable additional ex- 
pense. However, if it was not yet possible to publish a new edi- 
tion of the Index, the plan adopted was the best possible, and 
nobody will criticize Christensen for not doing more than was 
possible. 
The introduction notes the fact that a thorough revision of 
the generic nomenclature is very much needed, and the Supple- 
ment, in the form in which it appears, is the most striking single 
piece of evidence which has yet appeared of the pressing ur- 
gency of such a revision. There is, unfortunately, no present 
method of compelling writers on ferns to adopt any particular 
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