ANNIVEKSAEY ADDRESS OP THE PRESIDENT. 67 



fathoms deep. Moreover Barbadoes is said not to be the only 

 West Indian Island in which Radiolarian deposits occur, so that 

 there is a probability, as might have been anticipated, that snbsi- 

 l^nces and elevatioDS of the character mentioned affected considerable 

 areas. 



IV. Uelations between Distribution of Animals and Land-areas. — 

 The last argument may not be strictly geological, but all who 

 recognize how intimately the story of the earth is bound up with 

 that of its inhabitants will have little doubt that the present 

 distribution of animals and plants is of the highest geological 

 importance, and that the existence of particular forms of living 

 beings in continents and islands is the result and the record of the 

 history of those areas and of their connexions with each other. 

 There can be no doubt, in short, that most important testimony as 

 to the distribution of land and water in past epochs is afforded 

 by the range of living species and genera. The information on 

 the subject of distribution at the present day is considerable, pro- 

 bably more extensive and nearer completion, so far as regards 

 vertebrate animals and phanerogamous plants, than that relating to 

 the geology of the different regions. Moreover the question of 

 zoological distribution has been ably treated by one of the first 

 biologists of the day, Mr. Alfred Wallace, who has in his later 

 works unhesitatingly given his adhesion * to the doctrine of perm- 

 anent oceanic and continental areas in almost its extreme form. 

 Just twenty years ago the question of distribution was dealt with 

 by Professer Huxley in an address to this Society, and my only 

 excuse for referring to a subject already treated by so high an 

 authority, is that the aspect of the question has entirely changed 

 since 1870, that our knowledge has greatly increased, that the 

 subject has been widely discussed, that the oceans have been better 

 surveyed, and that we are in the presence of an entirely different 

 theory of the distribution of land in past ages from that which 

 prevailed amongst geologists when Professor Huxley's address was 

 written. It is essential to add that, whereas my great predecessor 

 felt called upon to prove the theory of evolution before applying it, 

 we may now regard the doctrine as firmly established. 



In all the remarks which follow I shall assume as an accepted 

 fact, not only that all species of a genus, all genera of a family, and 

 all families in an order, class, or subkingdom, are descended from 



* ' Island Life,' chap. vi. ; ' Darwinism,' pp. 341, &c. 



