Alfred Russel Wallace 



as to be a source of difficulty. I have also to thank you for 

 your papers, one of which I had read before in the Natural 

 History Review, but I am very glad of a separate copy. I 

 am rather perplexed by Darwin speculating on the pos- 

 sibility of New Zealand having once been united with Aus- 

 tralia (p. 446, 4th Ed.). The puzzle is greater than I can 

 get over, even looking upon it as an oceanic island. Why 

 should there have been no mammalia, rodents and marsu- 

 pials, or only one mouse ? Even if the Glacial period was 

 such that it was enveloped in a Greenlandic winding-sheet, 

 there would have been some Antarctic animals ? It cannot 

 be modern, seeing the height of those alps. It may have 

 been a set of separate smaller islands, an archipelago since 

 united into fewer. No savages could have extirpated 

 mammalia, besides we should have found them fossil in 

 the same places with all those species of extinct Dinornis 

 which have come to light. Perhaps you will say that the 

 absence of mammalia in New Caledonia is a corresponding 

 fact. 



This reminds me of another difficulty. On the hypo- 

 thesis of the coral islands being the last remnants of a 

 submerged continent, ought they not to have in them a 

 crowd of peculiar and endemic types, each rivalling St. 

 Helena, instead of which I believe they are very poor [in] 

 peculiar genera. Have they all got submerged for a short 

 time during the ups and downs to which they have been 

 subjected, Tahiti and some others having been built up by 

 volcanic action in the Pliocene period ? Madeira and the 

 Canaries were islands in the Upper Miocene ocean, and 

 may therefore well have peculiar endemic types of very 

 old date, and destroyed elsewhere. I have just got in 

 Wollaston's '' Coleoptera Atlantidum," and shall be glad to 

 lend it you when I have read the Introduction. He goes 

 in for continental extension, which only costs him two 



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