THEOEY OP 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 Grould * 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 sorohinula 

 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 Neiirotrichus 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, hut, 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 X and Professor Edgworth 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 



* Gotdd, A., " Eemarks on Mollusks," p. 78. 



t Murray, A., " Geograpliical Eelations of Coleopterous Faunas," p. 37. 

 X Sollas, W. J., "The AtoU of Funafuti." 

 L.A. T 



