338 GOTE TURESSON 
gins (at about Kylsgard). The mixed populations in the transition 
belts between the distribution areas of the different types have already 
been discussed. 
The map of Scania (fig. 77) reproduced here and showing schema- 
tically the distribution areas of the different coast types of this pro- 
vince should be consulted in this connection. 
3. THE LOCAL DIFFERENTIATION OF THE HABITAT TYPE 
FROM THE SPECIES-POPULATION. 
When, in passing from South to North or from the plains into Alpine 
levels, a zonation of a species-population into different climatic types, 
corresponding to the changes in climate, is found to take place, the 
conviction is forced upon us that these types are intimately related to the 
different external factors. The repetition of the zonation in regions far 
distant from each other, as for instance the zonation of Armeria vulga- 
ris on the coasts of Norway and Greenland, increases the strength of 
this assumption. The further question whether this repetition is due 
to a local differentiation of the respective types from the species-popu- 
lation, or is the result of a migration of an once differentiated type into 
suitable habitats, becomes of great interest in this connection. In the 
following an attempt will be made to throw some light upon this 
question by the aid of the cultivated habitat types of H. umbellatum. 
It is convenient to start with the type of the shifting beach-dunes. 
If the collections of leaves of this type (figs. 67-72) are examined, it 
is at once seen that the series from the various places exhibit consi- 
derable differences. While the series from the Sandhammar set (fig. 
72) fairly closely resembles the Halmstad set (fig. 68), important dif- 
ferences as to leaf shape are seen in the Falkenberg set (fig. 67). 
These individuals do not have the linear leaves typical of the first 
series, but have leaves which are much pointed and remarkably broad 
in their lower part. Even in the individuals with quite narrow leaves 
the characteristic leaf-base is always to be seen. Thus these leaves 
show resemblances both to the cliff-type (which has the leaves broadest 
in the lower half) and to the dune type at Halmstad and Sandhammar 
(which has long and narrow leaves). Now when the Falkenberg dune 
population as a whole shows these undoubtedly non-essential leaf-cha- 
racteristics, the assumption appears most reasonable that the type in 
question has. become locally differentiated from a mixed population of 
the cliff-type (which is already found typically at Varberg) and of the 
dune type of the south. 
