cHAr. in.] CONTINUITY WITH NORTH AMERICA. 43 



strata of Norfolk and Suffolk, and derived from the older 

 marine accumulations. 



Continuity with North America. 



The researches of Professor Heer into the fossil vege- 

 tation of the Continent, Britain, Iceland, Spitzbergen, 

 Greenland, and Grinnell-land, prove that the whole of 

 this portion of the earth's surface was dry land in the 

 early Tertiary period, offering free means of migration 

 to plants and animals from the Polar regions into 

 America on the one hand, and Europe on the other. 

 Among the forms common to the Meiocenes of Europe 

 and the flora of the American continent, we may notice 

 the mammoth tree, magnolia, tulip tree, red wood, and 

 swamp cypress (Taxodium disticum) ; among the mam- 

 malia common to both, the Hipparion; among the 

 reptilia, the alligator-tortoise 1 and a frog, 2 allied to the 

 horned species of Brazil. Similar evidence of direct 

 communication between the two continents is afforded 

 by the Meiocene insects 3 and land crabs (Gecarcinus) of 

 Oeningen, in Switzerland. We may therefore conclude 

 that the barrier of land connecting the British area with 

 Iceland and Greenland in the Eocene, existed in the 

 Meiocene age, and allowed plants which were Eocene in 

 the Polar regions to flourish in Meiocene Europe. The 

 five-hundred fathom line indicates the probable coast-line 



1 Chelydra Murchisoni, Bell. The representative species inhabits the 

 rivers and lakes of the United States, from New York to Florida, and is 

 a rapacious animal, living on fishes, amphibia, and young birds. 



2 Latonia Seyfriedi, Meyer. According to Heer, allied to Ceratophrys 

 cornuta. 



5 The genus Naupactus and others. See Heer, Primeval World of Swit- 

 zerland', ii. c. i. 



