r
heterocercal fish are embryonic as compared with the later homocercal."
He shows that facts do not support this view, and concludes generally
"that there is no real parallel between the successive forms assumed in
the development of the life of the individual at present and those which
have appeared at different epochs in the past.") I heard some time ago
that before long I might congratulate you on becoming a married man.
(40/2. Mr. Huxley was married July 21st, 1855.) From my own experience
of some fifteen years, I am very sure that there is nothing in this
wide world which more deserves congratulation, and most sincerely and
heartily do I congratulate you, and wish you many years of as much
happiness as this world can afford.

LETTER 41. TO J.D. HOOKER.

(41/1. The following letter illustrates Darwin's work on aberrant
genera. In the "Origin," Edition I., page 429, he wrote: "The more
aberrant any form is, the greater must be the number of connecting forms
which, on my theory, have been exterminated and utterly lost. And we
have some evidence of aberrant forms having suffered severely from
extinction, for they are generally represented by extremely few species;
and such species as do occur are generally very distinct from each
other, which again implies extinction.")

Down, November 15th [1855?].

In Schoenherr's Catalogue of Curculionidae (41/2. "Genera et Species
Curculionidum." (C.J. Schoenherr: Paris, 1833-38.)), the 6,717 species
are on an average 10.17 to a genus. Waterhouse (who knows the group
well, and who has published on fewness of species in aberrant genera)
has given me a list of 62 aberrant genera, and these have on an average
7.6 species; and if one single genus be removed (and which I cannot yet
believe ought to be considered aberrant), then the 61 aberrant genera
would have only 4.91 species on an average. I tested these results in
another way. I found in Schoenherr 9 families, including only 11 genera,
and these genera (9 of which were in Waterhouse's list) I found included
only 3.36 species on an average.

This last result led me to Lindley's "Vegetable Kingdom," in which I
found (excluding thallogens and acrogens) that the genera include each
10.46 species (how near by chance to the Curculionidae), and I find 21
orders including single genera, and these 21 genera have on average 7.95
species; but if Lindley is right that Erythroxylon (with its 75 species)
ought to be amongst the Malpighi