EUROPEAN INVASION 
211 
reveal a still more extraordinary phenomenon in distribution. 
We may imagine, and many people actually do, that the power 
of wind and waves 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 
[south 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 Californian 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, II. A., “ Manual of Conchology,” IX., p. 196. 
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