, that new
species were created by variation and in the way of ordinary generation.
Your last letter was a great help to me, for it was a relief to find
that the Lombok barrier was not so complete 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
possibility of New Zealand having once been united with Australia (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 marsupials, 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 hypothesis 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.
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