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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 239

observed the same peculiarity in the anthropoid brain. Thus he remarks
:—u Meine Studien fiihrten mich dahin, dass ein Weitnachaus-
senragen der parieto-occipital-Spalte mit dem sie umrandenden
Windungsbogen eine Eigenthiimlichkeit des Anthropoiden-Gehirnes, also
inferiorer Entwicklung sei, wahrend gerade im Gegentheile eine starke
Entwicklung des unteren Scheitellappens ein Signum hoherer Entwicklung
abgebe."

Inclination of the sagittal part of the Intraparietal sulcus.—The inclination
of the sagittal part of the intraparietal sulcus does not entirely depend upon
the degree of development of the first annectant gyrus. This of course
affects the position of its hinder end; but its anterior end at its point of
junction with the postcentral sulcus is also liable to changes of level, and
these likewise influence the inclination of the furrow.

The inclination of the furrow can best be appreciated by measuring the
angle which is formed by the intersection of two lines drawn backwards
which correspond respectively to the mesial plane and to the sagittal part
of the sulcus. This angle may be termed the " intraparietal angle." I
have determined it in a number of brains by means of the American
apparatus for tracing orthogonal projections of the skull. My plan of
operation has been the following: One pin was introduced into the hemisphere
at the junction of the sagittal portion of the intraparietal sulcus
with the postcentral furrow, and another pin into the hinder end of the
sulcus at its point of bifurcation into the sulcus transversus. A line drawn
between the two pin-heads was considered to give the direction of the
sulcus. A number of parallel straight lines were then drawn upon the
varnished plate of glass of the instrument, and the hemisphere was adjusted
below this, so that whilst one of these lines corresponded with the mesial
plane of the brain another passed through the hinder pin-head or posterior
end of the sulcus. By means of the periglyph the accuracy of this adjustment
could easily be tested, and the position of the hinder pin-head on the
straight line which passed through it indicated. The position of the second
pin-head at the other end of the sulcus was then determined by the periglyph
and marked on the glass. By joining the marks on the glass, corresponding
to the pin-heads in the brain, the angle which this line formed