74 
Many of these relics are, as Wahlgren has stated in the 
case of the species occurring in the “alvar“ of Oland, xerotherm, 
and may be supposed to have immigrated during a period with a 
drier and more Continental climate than the present. 
During the Ancylus-transgression the land-bridge, as well as 
the supposed connection with Gottland, was submerged. Munthe 
has suggested that perhaps later on a second land-connection was 
established, and Wahlgren has for zoogeographical reasons adopted 
this hypothesis. He points out that many of the xerophilous insects 
of Oland require chiefly a climate with a high diurnal tempera¬ 
ture in summer and therefore may have immigrated early in the 
Ancylus period ( Coscinia striata, Acidalia violata, A. rubiginala; 
to the same group evidently belong many other of the insects 
of Bornholm); other animals are more pronouncedly thermophil- 
ous and have, in his opinion, immigrated over the second land- 
connection during the later part of the Ancylus epoch (Sern ån¬ 
de r’s boreal period) ( Rana agilis , Selidoseina ericetaria ; to these 
species also Papa avenacea and Agrotis janthina). There are, 
as far as I can see, no adequate proofs of this hypothesis. We 
know now that the climate during and after the melting of the 
land-ice improved much more rapidly than was previously supposed 
to be the case, and it is quite possible that even before the An¬ 
cylus Lake had reached its highest level in the South the climate 
was not only drier but also warmer than it is to-day. 
Finallv I wish to add a few remarks upon the negative features 
of the fauna of Bornholm. Many animals that are now absent 
from Bornholm may have lived there at an earlier period, but 
have died out, as a result, for instance, of the disappearance of 
the woods (the present woods are mostly cultivated). It is of great 
interest to note the absence of Talpa europæa in Bornholm, Oland 
and Gottland. If Bornholm has been connected with North Ger- 
many in post-glacial times, the absence of this animal can be 
explained only by the assumption that it is a comparatively late 
immigrant, which reached the northern Baltic area after the dis¬ 
appearance of the land-bridge. But the mole, which cannot pos- 
sibly cross even a narrow strait, must have reached Scandinavia 
during the Ancylus epoch, when Sweden was connected with Ger- 
many by Denmark. With the assumptions stated above, the date 
