of Somnolence. (See the profile view of the cranium.)

The upper portion of the middle lobe has been given the name of
parietal, as it has a general correspondence with the parietal bones,
while the occipital lobe has a general correspondence in position with
the occipital bone, as will be seen by comparing the plan of the brain
seen in profile with the engraving of the cranium.

The _plan_ of the brain is given, instead of an engraving of the
actual convoluted surface, to simplify the study to the learner. An
examination of the brain itself or of a good model offers at first
sight such a vague and irregular mass of convolutions, differing so
much in different brains, that any systematic arrangement would seem
impossible. But by studying the subject more extensively and
considering the structure of the simpler brains of animals, in which
the complexity of the human brain is reduced to simpler forms, a mode
of grouping and classifying the convolutions has been adopted by
anatomists which is illustrated by the engraving, in which we see, not
the numerous convolutions of a well developed human brain, but the
groups in which they have been arranged by the aid of comparative
anatomy.

The front lobe is grouped into the superior, middle, and inferior
convolutions, or groups of convolutions, and the ascending frontal;
but the inspection of a brain would show an irregularity of forms in
which a casual observer would be puzzled to trace this arrangement.

The appearance of the brain, divested of its membranes, when we look
upon its superior surface, is shown in the annexed engraving, in which
it is presented as it lies in the head when the cranium and membranes
are removed which form the rim of the figure. The front lobe is the
upper portion, and the outline of the nose is just visible. In the
full exposition of this subject hereafter in a larger work, I propose
to show the exact seats of the various functions in the convolutions,
which are much more irregular than the angular figures we make on the
surface of the head to show the average positions of organs. Of course
no intelligent person supposes the psychological maps and busts of the
organs to be representations of the brain, or anything more than
approximations to the true interior organology, which, however, do not
lead to any great error, as adjacent portions of convolutions have
very analogous functions.

[Illustration]

When we place the brain on its upper surfa