504 SMITHSONIAN MISCELLANEOUS COLLECTIONS [voL. 48 
Assuming that it has been made to appear probable that the “ At- 
lantic ” element of the west Norway biota invaded that country from 
Scotland, there is yet another question which must be considered, 
viz., did these plants and animals come simultaneously, or do they 
belong to two different invasions? Many of the plants require rather 
diverse climatic conditions, and so do some of the animals. As- 
suredly, the red deer and the lemming do not belong to the same 
life zone! Nevertheless, there does not seem to be any good rea- 
son why the land bridge in question could not have presented 
climatal conditions sufficiently different for the two (adjacent) life 
zones. We have presupposed a warm current laving its western 
shore and a more or less cold sea limiting it on the east, thus creating 
conditions extreme enough for our purpose. Of course, if there 
were two separate land connections, one before and the other after 
the neoglacial maximum, the problem of the two life zones would 
be correspondingly simplified. 
‘ 
It should be clearly understood that by avoiding the term “ inter- 
glacial”’ in the discussion of the existence of a Scoto-Norwegian 
land bridge since the megaglacial maximum I have tried to keep 
out of any controversy over the question whether there were more 
than one glacial period in Scandinavia. As far as west Norway 
is concerned it appears to me that the probability is against two 
separate and distinct glaciations interrupted by a long period of 
mild climatic conditions. From the character of the animals and 
plants whose occurrence in western Norway I am attributing to an 
invasion following the megaglacial maximum and preceding that 
of the neoglacial stage, the conclusion may be drawn that the climate, 
even along the west coast of the land bridge, was not milder than 
that of the present time, but that, on the whole, it had a more conti- 
nental character owing to the greater land area to the west. With 
the depression of the land, from having stood so high as to shut off 
the Gulf Stream, toa level of say 200 sea-meters, and the consequent 
reappearance of that temperating agency, an amelioration of the 
climate must have taken place, but while the glaciers retreated some- 
what into the interior, it does not seem likely that they left the coast 
altogether. At the Norwegian end of the land bridge we may 
perhaps have had conditions similar to those of Norway under the 
Arctic circle or like those in the Mt. Elias region of Alaska at the 
present time, while from the interior vast glaciers, much larger than 
Justedalsbre or Folgefonn to-day, sent occasional arms to the sea. 
The neoglacial increase there may then be regarded only as a recrud- 
