A.NN1VEESAEY ADDRESS OP THE PEESIDENT. I07 



arrangement of the land-areas would perhaps explain the distri- 

 bution of the modern flora in belts, as shown by Mr. Thistelton 

 Dyer, and account for the dissemination round so large a part of 

 the globe of a great tropical flora and of certain tropical forms of 

 animal life, for instance, Iguanidce, apodous Batrachians, and some 

 families of land-mollusca. 



It will thus be seen that whilst the general permanence of ocean- 

 basins and continental areas cannot be said to be established on 

 anything like firm proof, the general evidence in favour of this view 

 is very strong. But there is no evidence whatever in favour of the 

 extreme view accepted by some physicists and geologists that every 

 ocean-bed now more than 1000 fathoms deep has always been ocean, 

 and that no part of the continental area has ever been beneath the 

 deep sea. Not only is there clear proof that some land-areas lying 

 within continental limits have at a comparatively recent date been 

 submerged over 1000 fathoms, whilst sea-bottoms now over 1000 

 fathoms deep must have been land in part of the Tertiary era, but 

 there are a mass of facts both geological and biological in favour 

 of land-connexion having formerly existed in certain cases across 

 , what are now broad and deep oceans. 



I have not hitherto adverted to the question of the origin of coral 

 atolls for two reasons, first that it is far better to discuss the ques- 

 tion of the permanence of ocean-basins on evidence which is not a 

 matter of dispute, secondly that I have a strong impression, almost 

 amounting to conviction, that a belief in the unchangeable character 

 of the oceanic area has been the origin of much of the opposition to 

 Darwin's theory of the connexion between atolls and areas of sub- 

 sidence *. It will, however, be manifest that i£, as I think is pro- 

 bable, there was a belt of land across the Indian Ocean in Cretaceous 

 times, represented during the greater part of the Tertiary era by 

 large islands, and if the position of those islands is now indicated 

 by the atolls of the Laccadives and Maldives and the great sunken 

 atoll-shaped banks of Chagos and Saya de Malha, it is clearly con- 

 sistent with this theory that atolls, as a rule, occupy areas of depres- 

 sion. , 



* I cannot but think that this is especially the case with one of the principal 

 writers on the subject, Mr. John Murray, and to this I attribute the circumstance 

 that, whilst calling attention to the submarine "elevations" which rise from 

 considerable depths to within a few hundred fathoms of the surface, he has 

 omitted to notice that such shoal-areas may be sunken islands, and result 

 from subsidence, not elevation. 



