104 THE AMERICAN NATURALIST. | [Vor. XXXV. 
Cuniculus torquatus, the presence of which would rather work 
against Dr. Scharff's theory, since it does not occur in Scandi- 
navia at all. The Spitsbergen reindeer, on the other hand, is 
so different from the one of Norway that it does not seem 
probable that one is the lineal descendant of the other. Add 
to this that the sea between Norway and Spitsbergen is more 
than 300 meters deep, and an exchange of terrestrial mammals 
between these two countries becomes highly improbable. 
Before proceeding any farther I wish to state that while 
disagreeing with Dr. Scharff in his supposition of a continuous 
connection between Greenland and Spitsbergen and between 
the latter and Norway, over which his Arctic invaders might 
have traveled, I am in full accord with him in regard to the 
land bridge between Norway and Great Britain across the North 
Sea, and also in his conclusion that most of the immigrants 
which he designates as Arctic belong to an invasion different 
from and considerably older than the great Siberian immigra- 
tion. That I also accept the continuity of Great Britain with 
Ireland and France, the breaking down of this connection 
between the two former prior to that between England and 
France, goes without saying ; but I do not exactly agree with 
him in his views as to all the higher vertebrates which he 
attributes to this invasion. 
To any one who is familiar with the present and past dis- 
tribution of the Norwegian lemming (Myodes lemmus}y it 
must be somewhat surprising to find it included by Dr. Scharff 
among his Siberian colonists, rather than among the Arctic 
invaders. The reasons are obvious, vzz., first, because this 
rodent does not occur in America and Greenland, whence the 
Arctic invasion is supposed to have come; second, because it 
has not as yet been found fossil in Ireland, where, according to 
the theory, it should have occurred if it arrived in Great Britain 
before the land connection with Ireland broke down, an event 
later than the arrival of the Arctic invaders according to Dr. 
Scharff's chronology. This negative evidence, however, would 
have been counterbalanced, I imagine, by the fact that remains 
1 i i : 
I adhere in this review to the nomenclature used by Dr. Scharff without 
regard to my own preference in the matter, in order to avoid confusion. 
