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Xll

Cunningham Memoirs.

border which corresponds to the level of the outer part of the superciliary
margin of the frontal lobe. This border is very far from being horizontal.
Its outer part is on a much higher level than the inner part. As it is
traced inwards it is seen to take a sudden curve downwards towards the
cribriform plate of the ethmoid bone, where it merges with the mesial
border. A line drawn horizontally inwards from the high outer part of
the superciliary border of the frontal lobe cuts the mesial border of the
cerebrum at the point which I arbitrarily selected as the anterior end of
the cerebrum. It lies, as a rule, just below the most projecting part.
Behind I took the most prominent part of the occipital pole.

The first of these points may be distinguished as the frontal point, and
the latter as the occipital point. Further, the distance between these two
points measured along the upper border of the hemisphere may be termed
the mesial length.

Illustrations.—With very few exceptions, the figures in the eight
Plates which accompany this Memoir were drawn upon the stone from
photographs of the specimens which are depicted. Mr. Rubert Boyce, M.B.,
furnished me with photographs of the early brains preserved in the
Museum of University College, London, whilst my Assistant, Mr. F.
Dixon, B.A., and Dr. L. Macrory, executed the photographs from which
the majority of the other figures have been taken. I am greatly indebted
to these gentlemen for the valuable assistance they have given me.

In the course of my work I found the apparatus for tracing orthogonal
projections of the skull devised by Dr. W. Matthews* of the United States
Army of very great service. A number of outline tracings obtained in
this way are reproduced in the text in Chapters IV. and V. But in
addition to affording a means of obtaining accurate illustrations, the
apparatus proved most useful in enabling me to reduce the sulci on the
surface of cerebral hemispheres under consideration into a series of
trustworthy charts, which threw a considerable amount of light upon the
fissural arrangement in each case, and rendered the comparative study of
the sulci easier. By it also the various angles (e. g. Rolandic angle,
intraparietal angle, &c. &c.) can be determined with great accuracy.

* For a description of this apparatus, vide " Journal of Anatomy and Physiology," vol. xxi., p. 43.