RECENT OCEANIC CAUSEWAYS. 541 



so represented in the New World by identical species. Among the 

 arborescent plants, alders, willows, junipers, and the common yew 

 exist in the cold or temperate regions of both worlds. While we 

 refrain from dwelling on the grasses and ferns, the dissemination 

 of which to great distances is one of the most common phenom- 

 ena,* we are able to cite plants which seem hardly adapted to leap 

 over the arms of the sea, such as orchids and lilies of northern 

 Europe, which are also common in North America. 



The numerous world of insects furnishes hundreds of exam- 

 ples of species that have passed across from the arctic regions of 

 Europe into America. Of the beetles, insects generally sedentary 

 and possessed of means of locomotion so inferior that they would 

 hardly venture to cross a sea with them, we can mention not less 

 than three or four hundred species as common to both continents. 

 We are particularly struck with the number of carnivorous spe- 

 cies {Carabides), which, living on the land and hiding under 

 stones, are disseminated very slowly. These species of carnivo- 

 rous Coleoptera may be followed from the north of the European 

 continent to Iceland, the shores of Greenland, Labrador, and 

 Canada, f It would be absurd to suppose that man has been able 

 in his migrations to carry such a multitude of the lower creatures 

 across the ocean. Notwithstanding the daily chances and the 

 continual transportation of all kinds of food-products, the com- 

 mon chafer of Europe has not been introduced at any point in 

 North America. 



Lepidopterous insects (butterflies and moths), aided by a favor- 

 able wind, are undoubtedly sometimes carried over the sea ; and 

 it is not impossible that when they fall upon a land remote from 

 the country of their origin they may live and propagate them- 

 selves there. These, however, are exceptional cases, while the 

 Lepidoptera of the New World may be counted by the legion. 

 The common vanessas of Europe abound in the northern parts 

 of America,! and the argynnes of Lapland and Iceland* and the 

 satyrs of the genus Chionobas live also in Labrador. The enu- 

 meration could be easily extended. 



It is fair to suppose that investigations properly directed 

 would enable us to recognize, in some American forms very close 

 to the European, local varieties of the same species. It may 



* M. 0. Francliet, a botanist attached to the Museum of Natural History, has made, at 

 my request, a complete examination of the plants of northern Europe which are diffused to 

 a greater or less extent in North America. 



f Bldhera ardica, Nebria nivalix, Bemhid'mm Grapei, Patrohus sepicntrwiix, Pterosti- 

 chus vitreus, P. arcticola, Amara erratica, A. inierstidaHs, A. brunnea, PlaUjrus Boge- 

 manni, Miscodera arciica. 



I Vanessa anfiopa, V. Paolychlorus, V. Urtica, V. Atalanta, 



* Argynn'is Freya, A. Frigga. 



