75 
of the immigration of this mammal can be fixed within a very 
limited Space of time, viz. the interval between the Ancylus trans- 
gression and the Litorina subsidence (probably the period between 
7000 and 5000 B. C. according to De Geers chronology). This 
supposition cannot, however, be taken as certain until further proofs 
are furnished. 
Among the flora the beech is undoubtedly a late immigrant; 
paleontological facts prove that this tree reached Scandinavia during 
the later part of the Litorina epoch. In Bornholm the beeches are 
cultivated. It is interesting to State that this plant, which like the 
animals discussed above (land-shells, etc.) can cross the sea only 
by occasional accidents, has not immigrated to Bornholm, to Oland 
or to Gottland. 
30-9-19. 
