ifications of form and structure which obtain in organized
beings--the many lines of divergence from a central type, the increasing
efficiency and power of a particular organ through a succession of
allied species, and the remarkable persistence of unimportant parts such
as colour, texture of plumage and hair, form of horns or crests, through
a series of species differing considerably in more essential characters.
It also furnishes us with a reason for that "more specialized structure"
which Professor Owen states to be a characteristic of recent compared
with extinct forms, and which would evidently be the result of the
progressive modification of any organ applied to a special purpose in
the animal economy.

We believe we have now shown that there is a tendency in nature to the
continued progression of certain classes of _varieties_ further and
further from the original type--a progression to which there appears no
reason to assign any definite limits--and that the same principle which
produces this result in a state of nature will also explain why domestic
varieties have a tendency to revert to the original type. This
progression, by minute steps, in various directions, but always checked
and balanced by the necessary conditions, subject to which alone
existence can be preserved, may, it is believed, be followed out so as
to agree with all the phenomena presented by organized beings, their
extinction and succession in past ages, and all the extraordinary
modifications of form, instinct, and habits which they exhibit.

Ternate, February, 1858.

FOOTNOTES:

[A] This MS. work was never intended for publication, and therefore was
not written with care.--C. D. 1858.

[B] I can see no more difficulty in this, than in the planter improving
his varieties of the cotton plant.--C. D. 1858.

Contributions to the Anatomy and Natural History of the Cetacea. By R.
KNOX, Esq., M.D., F.R.S.E. Communicated by the Secretary.

[Received Oct. 6, 1857.]

Part I. THE DOLPHINS.

The dissection of the Cetacea, and more especially of the larger kinds,
is attended with great difficulty, and not unfrequently entails heavy
expenses on those who attempt it. For these reasons I have thought that
zoologists might be pleased to have, even now, submitted to them the
results of numerous dissections made many years ago, when, not stinted
in means, and having the aid of excellent assistants, I attempted the
dissection even of the gi