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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 237

of the interparietal furrow more than the first external annectant gyrus of
Gratiolet—that arched convolution which bounds the perpendicular fissure
towards the parietal region. Already the gradual increase in the development
of this convolution as we pass from the lower apes up to the
primates and its progressive transformation to a primary convolution,
justify the conjecture that it attains a special importance in the higher
animals, and also in man. For this annectant gyrus shows a greater difference
, according to sex, race, and individuality, than any other region
of the brain-cortex. In the female it is usually present in the form of a
simple smooth arch which surrounds the perpendicular fissure. Already,
for some years had I learnt to recognise this fact, and also the necessary
consequence that one could determine the sex by the form and arrangement
of this arching convolution, and the depth of the parieto-occipital
fissure. The shortness and the simplicity of the curve of this arching
gyrus is associated with a smaller depth of the perpendicular fissure, and
these peculiarities are very characteristic of the hemispheres of the female
brain. In cases where this convolution occupies a small amount of space on
the hemisphere, the ' Affenspalte' and the hinder end of the sagittal limb
of the interparietal sulcus become only slightly turned lateralwards, and it
therefore follows that the latter furrow assumes an oblique direction. . . .
In the female brain the entire extent of the superior parietal lobule, and
the first annectant gyrus, remain distinctly backward in their degree of
development, and these two factors together are the cause of the described
characteristic direction of the interparietal furrow. . . . Especially characteristic
of the male parietal lobe is the altered direction of the interparietal
sulcus, which assumes a more sagittal direction."*

I regret that I cannot confirm these observations of Rudinger. I have
found—(1) that the relative size of the arcus parieto-occipitalis (first annectant
gyrus) is not appreciably different in the male and the female;

(2) that it is relatively more bulky in the anthropoid apes than in man;

(3) that the obliquity of the sagittal portion of the intraparietal sulcus is
apparently more marked in the male than in the female ; (4) that it is in

* " Ein Beitrag zur Anatoniie der Affenspalte und der Interparietalfurche beim Afenschen
nach Race, Geschlecht und Individualitat." Henle's Festschrift, Bonn, 1882, pp. 194 and 195.