AMEEICAN 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), Dr. 

 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-Schmetterlinge," pp. 296298. 



