DERIVATION OF THE FLORA AND FAUNA 325 



without the help of some kind of closer contact with other lands. He looks 

 around for bridges in the shape of "stepping stones", just as Mayr does, "tem- 

 porarily connected or sufficiently close together". "It is," he continues, "a long 

 distance between Guam and Fiji and Tahiti and Hawaii, but if there were numer- 

 ous other islands spread conveniently between . . ."; speaking of the weevils of 

 Necker Island and of Nihoa, Wake and Laysan where, with the exception of Nihoa 

 with its endemic palm and Laysan, once the home of an endemic form of San- 

 tahun, no suitable host plants exist, he finds strong evidence for their represent- 

 ing "the last remnants of former forest insects, surviving along a route of migra- 

 tion, a land bridge of the past" — this applies, I daresay, to an earlier connection 

 between the links of the broken Hawaiian chain. However, it seems to me that 

 rows of "conveniently spaced stepping stones", sufficient to offer routes of migra- 

 tion from several directions, involve tectonic movements of considerable magnitude. 

 Few conscientious bridge-builders would argue that, for instance, a solid land 

 mass extended from Melanesia and Indonesia to Hawaii as a continuous open 

 road, it might have risen gradually from west to east — when the land upon 

 which the present Hawaiian Islands were built, was above the sea, the western 

 part of the bridge had disappeared; all that was left was a detached, "advanced" 

 portion of a borderland, the home of a facies of the Australian-Malaysian fauna 

 and flora, which gradually took possession of the rising volcanic soil of Hawaii. 



Chapter V. 



The Pacific Ocean and Continental Drift. 



It serves no purpose to dwell here at any length on Wegener's original 

 hypothesis, with which every biogeographer is familiar, but it may be useful to 

 scrutinize its bearing on Pacific problems in general and Juan Fernandez in par- 

 ticular. Before the breaking up of Pangaea, the Pacific Ocean was twice as wide 

 as now, an enormous water desert where no islands enlivened the seascape. The 

 entire sial crust revolved west, where festoons were successively split off from 

 the Asiatic-Australian land mass, got stuck in the sima forming one island arc 

 after the other, bordered on their outside by deep trenches. The Americas trav- 

 elled at a greater speed away from Europe-Africa, and the Pacific became less wide. 

 It is true that most of the island chains in the Pacific trend NW-SE, but there 

 are many islands that do not follow this pattern, among them Juan Fernandez; 

 nevertheless, even if he did not expressly state this, it seems clear that WEGENER 

 regarded all of them to be of the same origin. In an earlier paper [2J1) I re- 

 ferred briefly to what he said about Juan Fernandez; here I shall quote him in full 

 {280. 116). 



Die pazifischen Inseln (mitsamt ihrem submarinen Unterbau) warden in der Ver- 

 schiebungstheorie als von den Kontinentalschollen abgeloste Randketten betrachtet, die 

 bei der allgemeinen, vorwiegend westlich gerichteten Bewegung der Erdkruste liber den 

 Kern allmahlich nach Osten zuriickgeblieben sind. Ihre Heimat ware hiernach, ohne auf 



