AMERICAN APOLLOS 
91 
Asia to America of the genus is not a recent event. It 
must have taken place at a time sufficiently remote from 
the present to permit the gradual evolution of the two new 
species from the ancestral forms. This may possibly have 
coincided with the eastward advance of the mammals referred 
to. A land connection in the neighbourhood of Bering Strait 
would certainly have facilitated the dispersal of these butter¬ 
flies and other insects just as much as that of mammals. 
In a discussion on the relationship of the Asiatic and North 
American forms of another genus of butterfly (Vanessa), I)r. 
Standfuss * also supported the theory of the former land con¬ 
nection between Asia and North America in pre-Glacial times. 
The Glacial Epoch, he contends, subsequently segregated 
the butterfly fauna into insular districts in which many 
species survived, and whence they afterwards spread to other 
parts. 
Before we consider the land bridge problem from the point 
of view of the marine fauna, some remarks on the general 
character of the present mammalian fauna of Alaska will 
be of interest. Both Labrador and Newfoundland, the two 
districts in the east which seem to have been little affected by 
the Glacial drift, and on which the still existing mammalian 
fauna probably survived from pre-Glacial times, were found 
to contain a certain number of peculiar species. We should, 
therefore, expect such a vast region as Alaska, which was 
also scarcely affected by Glacial drift deposits, to contain 
even a larger number of indigenous species of mammals that 
survived the Ice Age in the country. We do not positively 
know that any mammals survived the Ice Age in Alaska, but 
since we are unacquainted with any reasons why they should 
not have done so, that assumption is warrantable. The num¬ 
ber of mammals peculiar to the country is surprisingly large, 
and this alone implies that these animals inhabited the 
country for a sufficiently long time to develop characters 
distinguishing them specifically from those of the neigh¬ 
bouring parts in North America. The objection has been 
raised that American naturalists hold somewhat narrower 
views as to specific distinctions than are current among 
* Standfuss, M., “ Palaearktische Gross-Sehmetterlinge,” pp. 296—298. 
