380 THE POPULAR SCIENCE MONTHLY. 



this question. Formerly there was a warm climate in the north dur- 

 ing the Tertiary period. This was a certain measurable time ago, 

 when the circumpolar regions had a warm average temperature, with 

 no winter, and the moths of the period were then substantially the 

 same species from Norway across Siberia to Greenland. During this 

 happy time happy, at least, so far as weather was concerned we 

 must imagine that no impediment existed to the migrations of animals 

 across what is now Behring Strait. It is probable, even, that the 

 Tertiary epoch, as it witnessed the first appearance of man, saw his 

 first wanderings in North America. He, too, came from Asia by way 

 of the north and Behring Strait. Evolution had performed sur- 

 prising work in the mean while with one branch of the human family, 

 members of which, landing from Scandinavian or Spanish ships, met, 

 upon American soil, the descendants of a migration from Asia to 

 America in a former geological period, and to the east ! At the close 

 of this Tertiary period of the earth's history, cold and snow and ice 

 set in ; the long winter of the ages made its appearance in the shape 

 of the Glacial epoch. The circumpolar moths, whose more humble 

 fortunes we must be content here alone to follow, were forced south- 

 ward gradually by the change in climate which gathered its frigid 

 strength in the north. The European, Asiatic, and American faunae 

 then became separated, the latter the most completely, and by barriers 

 both of ice and ocean. The American species of moths, which for- 

 merly lived upon the shores of the Arctic Ocean, were gradually forced 

 down, year by year, until they reached Mexico, or the elevated por- 

 tions of the Southern States. When the glaciers subsided, and the 

 floods of ice which had submerged the continents gradually melted 

 and slowly drained away, the moths, much changed by the long con- 

 flict, also retraced their steps northward. As marks of the retreat and 

 advance, colonies of moths were left on the mountains to tell of the 

 flood. At this time our " Western clawed cutworm" ( Copimamcstra 

 occidenta) had been long separated from its present European broth- 

 ers, and the differences by which we now recognize the two species as 

 distinct had become slowly established through a long series of suc- 

 ceeding generations. What miles of land and sea separate the two 

 to-day ! The descendants of a common circumpolar species find them- 

 selves partly in Germany, partly in Arizona, and the Southwestern ter- 

 ritory of the United States ! 



Let us turn back to the other theory, that of a submerged Atlantic 

 Continent. Whatever may be finally proved from geology as to the 

 existence of such an Atlantic bridge, it is clear that the myth of the 

 Atlantis must be separated from such facts, as being of much more 

 recent origin. Primitive man existed reons before the notions which 

 were worked into the poetic and semi-historical myth of the Hesperides 

 and Atlantidcs. The setting sun was followed by human eyes for un- 

 told ages, as it bathed itself in the golden flush of evening, and was 



