1 857.] CONTINENTAL EXTENSION. 109 



doctrine of subsidence ; indeed, from the quite independent 

 evidence of the Coral Reefs I coloured my original map (in my 

 Coral volume) of the Aru Islands as one of subsidence, but 

 got frightened and left it uncoloured. But I can see that you 

 are inclined to go much further than I am in regard to the 

 former connection of oceanic islands with continents. Ever 

 since poor E. Forbes propounded this doctrine, it has been 

 eagerly followed ; and Hooker elaborately discusses the 

 former connection of all the Antarctic Islands and New Zea- 

 land and South America. About a year ago I discussed this 

 subject much with Lyell and Hooker (for I shall have to treat 

 of it), and wrote out my arguments in opposition ; but you 

 will be glad to hear that neither Lyell nor Hooker thought 

 much of my arguments. Nevertheless, for once in my life, 

 I dare withstand the almost preternatural sagacity of Lyell. 



You ask about land-shells on islands far distant from con- 

 tinents : Madeira has a few identical with those of Europe, 

 and here the evidence is really good, as some of them are sub- 

 fossil. In the Pacific Islands there are cases of identity, which 

 I cannot at present persuade myself to account for by intro- 

 duction through man's agency ; although Dr. Aug. Gould has 

 conclusively shown that many land-shells have thus been 

 distributed over the Pacific by man's agency. These cases of 

 introduction are most plaguing. Have you not found it so in 

 the Malay Archipelago ? It has seemed to me in the lists of 

 mammals of Timor and other islands, that several in all pro- 

 bability have been naturalised. . . . 



You ask whether I shall discuss " man." I think I shall 

 avoid the whole subject, as so surrounded with prejudices ; 

 though I fully admit that it is the highest and most interesting 

 problem for the naturalist. My work, on which I have now 

 been at work more or less for twenty years, will not fix or 

 settle anything ; but I hope it will aid by giving a large col- 

 lection of facts, with one definite end. I get on very slowly, 

 partly from ill-health, partly from being a very slow worker. 



