understand rightly,
this is not the case; and such characters must have been independently
acquired by some means.

The two newest and most interesting points in your letter (and in,
as far as I think, your former paper) seem to me to be about senile
characteristics in one species appearing in succeeding species during
maturity; and secondly about certain degraded characters appearing in
the last species of a series. You ask for my opinion: I can only send
the conjectured impressions which have occurred to me and which are
not worth writing. (It ought to be known whether the senile character
appears before or after the period of active reproduction.) I should be
inclined to attribute the character in both your cases to the laws of
growth and descent, secondarily to Natural Selection. It has been an
error on my part, and a misfortune to me, that I did not largely discuss
what I mean by laws of growth at an early period in some of my books. I
have said something on this head in two new chapters in the last edition
of the "Origin." I should be happy to send you a copy of this edition,
if you do not possess it and care to have it. A man in extreme old age
differs much from a young man, and I presume every one would account for
this by failing powers of growth. On the other hand the skulls of some
mammals go on altering during maturity into advancing years; as do the
horns of the stag, the tail-feathers of some birds, the size of fishes
etc.; and all such differences I should attribute simply to the laws of
growth, as long as full vigour was retained. Endless other changes of
structure in successive species may, I believe, be accounted for by
various complex laws of growth. Now, any change of character thus
induced with advancing years in the individual might easily be inherited
at an earlier age than that at which it first supervened, and thus
become characteristic of the mature species; or again, such changes
would be apt to follow from variation, independently of inheritance,
under proper conditions. Therefore I should expect that characters of
this kind would often appear in later-formed species without the aid
of Natural Selection, or with its aid if the characters were of any
advantage. The longer I live, the more I become convinced how ignorant
we are of the extent to which all sorts of structures are serviceable
to each species. But that characters supervening during maturity in
one species should appear so regularl