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appl}^ it to a very interesting group, which shall embrace, of the new 

 world species, Fhilodice, Eriphy/e, Hagenii and Eurytheme; in the old 

 world, Chrysotheme. Other species may be, and no doubt are, in 

 direct descent from the common progenitor of the five, but these 

 form so compact a sub-group that they may be studied by themselves 

 to advantage. In one continent, Chiysotheme represents the ancient 

 species ; in the other continent, Eurytheme. This last presents itself 

 ill three distinct forms, or in other words, the species is tri-morphic, 

 while Chrysotheme presents but a single form. It has its variations, of 

 course, as does Fhilodice, for example, but these have not separated 

 into defined seasonal forms. Of the three forms of Eurytheme, 

 one appears in winter or early spring, according to the latitude, Ari- 

 adne ; the second succeeds it in late spring, Keewaydin : and the third 

 is the summer form, Eurytheme. The first is small, with a minimum 

 of orange, and that pale ; the second is larger, with orange deeper and 

 covering a larger part of the surface; the third is very large, and the 

 orange covers the whole surface, is intense and often iridescent. Kee- 

 waydin most approaches Chrysotheme, and Dr. Hagen assumes as a mat- 

 ter of course that it is Chrysotheme, neither more nor less, which from 

 its territory in south eastern Europe — Austria at the nearest, has 

 jumped over the longitudes, first to the Atlantic, then across that ocean, 

 and popped down in the interior of the Western Continent, hundreds 

 of miles beyond the seaboard, as if it had crossed in a balloon, and 

 been dropped like a sand bag ; here it has then taken possession of the 

 Mississippi Valley and westward, and has in course of its American so- 

 journ and travels, developed, the doctor says, both backward into a win- 

 ter form and forward into a summer form, which he has to concede are 

 distinct from anything seen in the territory of Chrysotheme ?X home. 

 Neitlier Chrysotheme, nor any form of Eurytheme, inhabits the boreal 

 regions of either Continent, and Eurytheme is scarcely known in British 

 America, even. Therefore for one to have been derived from the 

 other, or for the two to be the same thing, as I said before, presupposes 

 impossible conditions, and is simply preposterous. The reasonable 

 explanation of the resemblance between the two species is this : the 

 common progenitor of both inhabited the circum polar regions, and by 

 the glacial climate, which followed the temperate, was pushed south- 

 ward, one branch on one continent, the other on the other continent, 

 and for all the ages that have passed since' the parting, no possible 

 connection can have been between the two. Now what is the latest 

 date at which such a parting could have been possible ? It must, of 

 course, have been when North America and Europe were connected 

 through the polar regions, and the leading geologists assure us that 

 this occurred during the last glacial period, and that before the close 

 of it, the connection was broken, and finally. The close of the glacial 

 period is set down at 80,000 years ago, its beginning at 240,000, and 

 in the intervening ages all this southward migration of plants and in- 

 sects took place. And what is the state of things to-day as re- 

 gards these Coliads ? We find Chrysotheme, the present represen- 

 tative of the ancient species on one continent, a very constant 

 species, and entirely without defined seasonal forms ; we find 



