512 SMITHSONIAN MISCELLANEOUS COLLECTIONS. [voL. 48 
1. That if the characteristic and important portion of the animals 
and plants of west Norway, called the “Atlantic” biota, invaded. 
that country from Scotland, it came by way of a land bridge con- 
necting northern Scotland with western Norway north of 59° 
north latitude. 
2. That this land bridge existed after the first (Scandinavian) 
great glaciation. 
3. That part of this biota surely survived the second (Scandi- 
navian) glaciation along the west coast of Norway, and that pos- 
sibly the climate was not too severe for all to survive. 
4. That there is a possibility of a reestablishment of the land 
bridge during the “Upper Forestrian” stage with its congenial, 
more continental climate, during which the tenderer species may 
have immigrated, in case it should be proven that they could not 
have come with the hardier ones. 
X. SUMMARY 
The biota of west Norway between the parallels of 59° and 63° 
north latitude is composed of several elements, an important portion 
of which must have come from Scotland. 
Some of the most conspicuous members of this biota are even at 
the present time confined to this coastal region, while others of 
somewhat wider distribution clearly point to the same coast as their 
secondary center of dispersal. Numerous other species not modified 
specifically, or subspecifically, probably accompanied this peculiar 
biota, a fact which cannot be proven at present on account of the 
defective status of our knowledge. 
This.so-called “ Atlantic”? and “ Arctatlantic”’ biota consists of a 
large number of species, among which the following are some of 
the more conspicuous : 
(a) The whole floral element, termed the “Atlantic plants” by 
Blytt, consisting of about 60 species of vascular plants, 27 species 
of hepatice, etc. 
(b) That portion of the Scandinavian “Arctic” plants desig- 
nated in this paper as the “ Arctatlantic ” floral element. 
(c) A number of terrestrial invertebrate animals such as Helix 
(Tachea) nemoralis, among molluscs; several species of Helodrilus, 
among the earthworms; Ligyda oceanica, among the isopod crus- 
taceans ; Aporophyla nigra, among the noctuid moths; Bombus smit- 
tianus, among the bumblebees, and a whole series of “ Atlantic”’ 
lepidoptera, hemiptera, and coleoptera. 
