38 H. MØLHOLM HANSEN 
method is the only method for investigation of the vege- 
tation which, in determining the quantitative distribu- 
tion of the individual species, makes use of the flora list 
principle, a principle which has always formed the basis of scien- 
tific plant geography, and which must also be adopted in the doc- 
trine of formations if this branch of botany is to lay claim to 
scientific equality with the other phytogeographical branches of 
the science. 
In naming the individual types of vegetation, I have used the 
Icelandic names and thus adhered to a custom often adopted in 
plant geography, that of retaining old names where such were found. 
At the same time reference of my own more thoroughly investigated 
types to the previous, more diffusely treated types of vegetation has 
been avoided, and this is in so far fortunate as it would seem that 
the latter have been determined with more regard to their physi- 
ognomy than to their environment. On the whole, however, the 
boundary lines coincide. Some of the names have already been 
used by Helgi Jönsson (1895); for those which do not occur in 
his paper I am indebted to the courtesy of Icelandic farmers or to 
Magister Pälmi Hannesson. 
