THEOBY OF A PACIFIC CONTINENT 
321 
survey is that the American and Asiatic forms related to one 
another are in Asia mainly confined to the south-eastern 
border generally, or to Japan. Australia, New Zealand and 
New Guinea also possess a large number of species and genera 
very closely allied to west American ones. These seem rarely 
to extend further north in Asia than Japan. Are we to throw 
a bridge across the Pacific ocean from Japan in order to find a 
possible explanation of this former invasion of south Asiatic 
and Australian types into western America, or does any other 
theory meet all the facts of the case ? 
Since Dr. Augustus Gould * first mooted the hypothesis of 
a former Pacific continent about sixty years ago, the idea has 
been widely discussed by biologists and geologists. Mr. 
Murray’s f attention seems to have been first drawn to the 
subject by the occurrence of the beetle Meristhus sorobinula 
in Mexico and China, and by the presence of the mole Urotri- 
chus in California and Japan. The Japanese and Californian 
moles are no longer placed into the same genus, but no one 
doubts that the American Neurotrichus and Japanese Urotri- 
chus are very nearly related to one another and that they 
must have had a common ancestor. 
The supporters of the theory of the permanence of our great 
ocean basins explain such cases by means of a former Bering 
Strait land bridge, but, as already stated, the solution of this 
problem must be sought elsewhere. That several of the pre¬ 
mises on which the theory of the permanence of ocean basins 
is founded are incorrect has been demonstrated (pp. 274— 
277). Darwin’s theoretical considerations on the formation 
of coral reefs and atolls, which demanded a long continued 
subsidence of the mid-Pacific region, have been amply veri¬ 
fied. To put his subsidence theory to a practical test Darwin 
suggested that a boring should be made into one of the cores 
of an atoll. Through the perseverance and energy of Pro¬ 
fessor Sollas J and Professor Edgwort.h David a boring on 
Funafuti atoll was carried to a depth of one thousand one 
hundred and fourteen feet, where cores were obtained showing 
that the whole mass of rock was composed of pure coral. Since 
* Gould, A., “ Remarks on Mollusks,” p. 78. 
t Murray, A., “ Geographical Relations of Coleopterous Faunas,” p. 37. 
X Sollas, W. J., “ The Atoll of Funafuti.” 
L.A. 
Y 
