FLIGHT OF PLANTS AND ANIMALS. 441 



Washington, the Rocky Mountains, and in Labrador. Agrotis 

 Islandica is found in Iceland, Labrador, in the White Mount- 

 ains, and perhaps in Colorado. As on islands in the air, these 

 insects have been left by the retiring ice-flood during the open- 

 ing of the Quaternary. 



On inferior elevations, as on Mount Katahdin, in Maine, 

 where we now find no (Eneis butterflies, these may formerly 

 have existed, succumbing to a climate gradually increasing in 

 warmth from which they had no escape ; while the original 

 colonization, in the several instances, must have always greatly 

 depended upon local topography. 



In a Russian Government Report made in 1900, is found 

 a list of plants occurring in the provinces of Okhotsk and Kam- 

 chatka. This list contains 746 species of phaenogamous or 

 flowering plants, 173 identical species of which are common to 

 North America, that is, twenty-three per cent are found in 

 North America. Many of these species are distributed uni- 

 versally through the North Temperate Zone, and twenty-one 

 are known to have been introduced into America from Europe, 

 but have become naturalized. If now we compare the flora 

 of Manchuria, using the list published in the Russian Govern- 

 ment Report on Manchuria for 1897, with that on Kamchatka 

 and Okhotsk for 1900, we find that there are 193 identical 

 species common to both, that is, nearly twenty-six per cent, 

 only five per cent more than that with North America. Of 

 the 173 species common to North America and the Provinces 

 of Okhotsk and Kamchatka, seventy-seven are also found 

 in Manchuria. Out of the 284 genera found in Okhotsk 

 and Kamchatka there are sixty-two genera not to be found 

 in North America. This number will probably be increased 

 when the Kamchatkan flora has been better studied, for the 

 region is so inaccessible that the lists at present must be 

 quite incomplete. 



The following list gives the plants common to the Okhotsk- 

 Kamchatkan region and North America, those marked with 

 a (*} are common to Manchuria also. 



