Chapter III 



THE TRUE, PRE-HUMAN RELATIONSHIP BETWEEN THE 

 PALAEARCTIC AND NEARCTIC FAUNAS 



The so-called Amphiatlantic species 



The word "Amphiatlantic" (German: amphiatlantisch) was proposed by 0kland 

 (1927, p. 352) in order to cover animal (and of course, also plant) species common 

 to Europe and North America but absent from Asia and thus believed to form 

 instances of direct faunal exchange across the North Atlantic. The word would 

 be equally suitable for species common to Africa and Central or South America 

 (if any) but is here used in the same sense as by 0kland, for the northern continents 

 only. 



A true Amphiatlantic species occurs only in Europe (possibly also in the African 

 and Asiatic parts of the Mediterranean region) and the eastern parts of North 

 America. If the word "Amphiatlantic" is used as a historical, not merely as a 

 geographical concept, implying that a species so termed took part in a direct 

 faunal exchange across the North Atlantic, then even animals and plants with 

 a wider distribution, towards the east in the Old World, to the west in North 

 America, may be included, provided a pronounced gap can be demonstrated 

 somewhere in the continents surrounding the North Pacific. 



However, it is safer, at least for the moment, to keep such historical aspects 

 out of the picture. The main question would then be to judge whether a seem- 

 ingly Amphiatlantic distribution, in the restricted sense of the word, is an un- 

 questionable reality or only due to incomplete knowledge of the species' area. 

 The latter possibility must always be earnestly considered since the fauna, not 

 only of northern Asia but also of Western North America, is far from sufficiently 

 investigated in many groups of animals. 



This reservation cannot, however, conceal the fact that a long series of animal 

 species, belonging to different taxonomical and biological groups, show a perfectly 

 Amphiatlantic distribution, as is amply exemplified in the list of Eur-American 

 species (p. 17-124). Many of these have already been treated in the preceding 

 chapter of this book and their crossing of the Atlantic was proved (or at least 

 considered) as a quite late event, caused by introduction with man, mainly in the 

 direction from Europe to North America. 



