RECENT OCEANIC CAUSEWAYS. 54.3 



Nature on the two continents. The union between the continents 

 probably existed only in the north, perhaps above the fiftieth 

 degree of latitude. If we follow the most eastern parts of Asia, 

 northern Japan, Siberia, and Kamchatka, which are separated 

 from America by Bering Strait, or if we proceed from the Ameri- 

 can side through the peninsula of Alaska and the chain of the 

 Aleutian Islands, we shall comprehend at once that only very 

 ordinary geological changes may have been sufficient to bring 

 about the separation of lands which had been long united. Look- 

 ing toward the extreme north, we find no other separation between 

 the Old and New Worlds than a simple arm of the sea, Bering 

 Strait. 



The study of living Nature in the arctic regions of Asia and 

 America is very instructive. Let us begin with examining the 

 vegetation. Some anemones and a ranunculus * of Siberia are 

 now common in North America. Another species of ranunculus f 

 is common to Japan, Kamchatka, Alaska, and northern and east- 

 ern America. While we admire the tulip tree % in the parks of 

 Europe, we recollect also that that beautiful exotic is one of the 

 glories of the North American flora. But the tulip tree has recently 

 been discovered in China. Then, there are the violets of Siberia 

 and Japan,* which are mingled also with the vegetation of North 

 America; and a vine {Vitus Lahrusca), now well known, reputed 

 American, which grows in Japan and a part of eastern Asia. A 

 maple || is common to Japan and North America, as are also 

 Spirceahetulifolia (birch-leaved spiraea) and Pole ntilla fragiformis 

 of the rose family, some saxifrages, a crassula {Penthorum se- 

 doides), various umbelliferous plants, the maritime alder, and a 

 few orchids and lilies. 



The animal world furnishes valuable evidences of our theory. 

 Concerning insects I will cite only the facts most demonstrative 

 of former communications. Some carnivorous beetles, the Ca- 

 rabs,^ insects remarkable for their forms and colors, wingless, and 

 having only their legs as means of locomotion, inhabitants of 

 eastern Siberia, are also found in the cold countries of North 

 America. I first saw collections made in California, after I had 

 already become familiar with the faunas of Europe, Asia, and 

 America. I was then surprised to see in those collections Euro- 

 pean and Asiatic forms which were believed to be entirely foreign 

 to America. A little French butterfly, also occurring in Siberia, 

 the valley of the Amoor, and Japan, was found on the western 

 coast of America. It appears to be unique in the color of its 

 wings, which are beautifully green on the lower sides. The like- 



* Eannneulus cj/mbalaria. f Trautvclieria palmata. % Liriodendron tulipifera, 



* Viola rostrata, V. Canadensis. || Acer spicatiim. 

 ^ Carabus Vie^yighosi , C. meander, C. truncaticoUis, C>jclu-us'anrfusticoUis. 



