was surprised to find how different, in fact, the anatomy of
the two great families was. Scarcely in any great natural family do we
find Cuvier's favourite theory of anatomical and physiological
co-relations so entirely at fault as in the Cetacea. The teeth or
whalebone, as natural-history characters, lead to no results; the whole
structure of the interior defies all _a-priori_ reasoning. The brain in
whalebone-whales does not fill the interior of the cranium; so that the
capacity of the one is no measure of the solid bulk of the other. Their
food is various, having no relation to the teeth or buccal appendages;
vascular structures surround the spinal marrow, and extend in the
_Balaenopterae_ into the cavity of the cranium, which seem to be without
any analogy in other mammals, or, at the least, a very obscure one, and
whose functions are wholly unknown.

Cetacea might with some propriety be divided into whales with whalebone,
and whales with teeth. Those with whalebone have rudimentary teeth in
both jaws in the foetal state. Fossil Cetacea exist, and they seem to
have been of both kinds, but, no doubt, were generically and
specifically distinct from the recent. Judging from the remains of those
I have seen, I am inclined to think that those with teeth were of a
stronger and firmer build in the skeleton than those called recent; that
the neck was longer, and the caudal portion of the column shorter than
in the recent kinds, and that they approached the Saurians in form.
There is a remarkable want of symmetry in the crania of some of the
Cetacea; but most remarkable is the cranium of the Narwhal. Of this fact
I have already spoken, in the article published in the Transactions of
the Royal Society of Edinburgh.

_Delphinus Phocaena. Dissection of a small Cetacean sent to me from
Orkney in the month of May 1835._--This species is said to abound on the
coasts, and to furnish a kind of fishery to the inhabitants. On
dissection we found 81 vertebrae, exclusive of the cephalic. The species
must be quite distinct from those previously and subsequently examined
by myself and many others, in which the number of vertebrae ranged from
61 to 66. It is also, I think, distinct from the specimen I saw in Dr.
R. Hunter's Museum in Glasgow, in which the number of vertebrae was 90,
exclusive of the cephalic in all the cases. Thus it stands with regard
to the Cetacea called Porpoises and Dolphins.

In certain species of _Delphinus_ the v