270 CHAPTER III 



the Icelandic, but also of the Greenlandic fauna could be the result of introduction 

 alone. At the same time we have denied that the said native element could have been 

 able to immigrate during present conditions, with the extension of land and sea 

 now existing in the North Atlantic region. One alternative only remains: the main 

 part of the fauna, especially of its soil-bound members, reached Iceland and Greenland 

 over a land-connection now submerged. 



This is the old hypothesis of a transatlantic bridge, eagerly advocated above all 

 by Sharff (1907, 1909, 191 1), but with the fundamental divergence that it did 

 not extend to the mainland of North America or at least, for some reason, it was 

 not faunistically effective as far west. 



The bottom configuration of the sea is rather favourable for the rise of the land- 

 connection required (fig. 43). A positive displacement of the shore-line amounting 

 to less than 600 meters would transform the Wyville-Thomson ridge into an 

 isthmus connecting Iceland and Greenland with the enlarged European continent 

 north of the present Scotland but also, it should be pointed out, via EUesmere Is- 

 land with Baffin Island. It would require very little more uplift to shape another 

 direct connection between Greenland and southern Baffin Island. 



An important question is whether an un-interrupted connection would be necess- 

 ary in order to allow an immigration of the said faunal element from Europe to 

 Iceland and Greenland. Considering its large share of flightless forms, in Iceland 

 26 species of 56 (46 per cent), in Greenland 6 of 11 (55 per cent), constituting the 

 Palaearctic element, the answer seems to be in the affirmative. Ocean water of 

 more than 30 pro mille salinity causes physiological desiccation of a terrestrial 

 animal (Palmen, 1944, p. 155 a.f.; Lindroth, 1949, pp. 600, 613). Furthermore, the 

 heavy Weevils, such as Otiorrhynchus arcticus O. Fbr., perhaps the zoogeographic- 

 ally most important member of the Iceland-Greenland fauna (fig. 41), soon are sunk 

 to the bottom by the lapping waves (Lindroth, 193 1, p. 485). Even the Channel, 

 only 31 km. at its narrowest, constitutes a marked faunistic barrier (Lindroth, 

 1949, p. 613), though the British Isles were connected with the mainland in early 

 postglacial times. The unbridgeable obstacle to flightless insects formed by the 

 Davis Strait has just been demonstrated. 



When it comes to dating the existence of the assumed Scotland-Greenland bridge 

 a biologist is largely up in the air. This much is certain, however, from geological 

 evidences: it cannot have persisted in late glacial or postglacial times. On the 

 other hand, the faunas of Iceland and Greenland bear no sign of long isolation. 

 Proposed endemic species all belong to insufficiently investigated animal groups, 

 such as Diptera, Hymenoptera and Hemiptera Homoptera among the insects. The 

 Coleoptera and Macrolepidoptera of these islands do not even contain clearly 

 defined endemic iwfepecies. Such, it is true, have been established among Mammals 



