10 Proceedings of the Royal Physical Society. 



notes. In one of these he refers to the observations of 

 Pourtales and others on a submarine calcareous deposit, 

 which, in some regions, is slowly being upraised to serve as a 

 foundation for coral-reefs. To the objection that if atolls 

 and barrier-reefs could be formed during a period of elevation 

 they ought to be found not merely at, or only slightly above, 

 sea-level, he replies that they are not, in fact, confined to 

 that limited zone, but that, even if they were, this would not 

 invalidate his conclusion that the reefs are due to a complex 

 co-operation of coral growth with the waves and currents of 

 the sea, and not to the one cause — the subsidence of entire 

 regions — invoked by Darwin. 



In the following year another contribution to the anti- 

 subsidence literature was made by Dr J. J. Eein, who, in an 

 interesting memoir on the physical geography of Bermuda, 

 offered some observations on the coral-reefs of these islands.^ 

 He suggested that the Bermuda group might originally have 

 been a submarine mountain or bank, on which colonies of 

 corals, moUusks, echinoderms, and other organisms took root, 

 flourishing in such abundance as gradually to raise the top of 

 the submerged ground to the zone in which reef-building 

 corals could begin. He adduced no evidence in support of 

 this suggestive forecast, further than that there is no proof in 

 Bermuda of subsidence, which, however, as Darwin had so 

 cogently shown, from the very fact of the movement being 

 downward, is, in most cases, not to be looked for. 



An important memoir, marking a totally new departure 

 in coral-reef literature, appeared in 1880, containing an 

 abstract of observations made by Mr Murray during the 

 great voyage of the ** Challenger." ^ The chief features of 

 this contribution may be thus briefly summarised. With 

 hardly an exception, the oceanic islands are of volcanic 

 origin, and it is therefore to be presumed that the submarine 

 ridges and peaks, which rise to within various distances from 

 the surface, are likewise due to the protrusion of volcanic 

 materials. There is thus no actual evidence of the still 



1 Bericht. Senckenberg, Naturforsch. Gesellscli., 1869-70, p. 157. See 

 Note, 2Jos(ca, p. 30. 



2 Proc. Roy. Soc, Edinb., 1879-80, x., p. 505. 



