EUKOPEAN INVASION . 211 



reveal a still more extraordinary phenomenon in distribution. 

 We may imagine, and many people actually do, that the power 

 of wind and wave's to carry objects from one part of the world 

 to another is almost unlimited. One of the most striking 

 and remarkable characters of California, however, is its very 

 close faunistic affinity with western Europe, Even the most 

 enthusiastic supporter of the flotsam- jetsam theory will feel 

 that some other cause than this must have been responsible in 

 producing this effect. A former land connection between the 

 two regions, without others being affected, seems out of the 

 question. Yet almost all those who have endeavoured to 

 explain the origin of this western fauna have preferred 

 to choose the old Bering Strait land connection as offer- 

 ing a safe passage to European animals, rather than 

 disturbing the general arrangement of the existing oceans 

 and continents. If the faunistic resemblance of Cali- 

 fornia to western Europe had really been caused by a 

 migration of animals from one area to the other across the 

 whole Asiatic continent, eastern Asia ought surely to show 

 affinity with California to a much more pronounced degree 

 than western Europe does. As a matter of fact, certain 

 groups in California are distinctly eastern Asiatic in affinity, 

 a,s I have just mentioned, while others are just as clearly; 

 isouth and west European in character. I have given a few 

 instances already of these faunistic relationships, and further 

 evidence will now be adduced in support of this statement. 



I think it was the snail Arianta arbustorum, so prominently 

 alluded to in my work on European animals, which first 

 drew the attention of American zoologists to this relation- 

 ship, for, as already remarked, a snail extremely similar in 

 appearance lives in California. Even Dr. Pilsbry * admits 

 that the resemblance in shell characters of the Calif ornian and 

 European species is astonishing, although he adds that it 

 is due to a purely secondary modification that these shells have 

 been moulded to a deceptive likeness, the genitalia having 

 been left unchanged to tell more faithfully the story of their 

 lineage. Having made an anatomical study of this Californian 

 Arianta-like group, Dr. Pilsbry arrives at the conclusion that 



* Pilsbry, H, A., " Manual of Conchology," IX., p. 196. 



P2 



