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246

Cunningham Memoirs.

frontalis medius are altogether opposed to those entertained by Eberstaller.
I shall state fully the grounds upon which my views are based when I come
to deal with the development of the frontal furrows in the human foetus,
and their arrangement in the apes.

Fig. 52.—Diagram to show correspondence between the prsecentral and intraparietal systems of furrows.

r. . .

Fissure of Eolando.

p.2

. Sulcus postcentralis superior of the intrap
. c. s.

Sulcus pracentralis superior.



parietal sulcus.

p. c. i.

Sulcus prsecentralis inferior.

p.3

. Eamus horizontalis of the intraparietal

h. .

Ramus horizontalis of the sulcus praecentralis



sulcus.



inferior.

p.* .

. Eamus occipitalis of the intraparietal sulcus.

f. m.

Sulcus frontalis medius.

s. t. .

. Sulcus occipitalis transversus of Ecker of the

■w.

Fronto-marginal sulcus of Wernicke.



intraparietal sulcus.

p.1

Sulcus postcentralis inferior of the intrap
. 0. .

. Parieto-occipital fissure.



parietal sulcus.





The first and second frontal furrows have also to be considered in our
study of the outer surface of the frontal lobe. Speaking of the connexion
which exists between these furrows and the prsecentral sulcus, Eberstaller
remarks that the first frontal furrow stands in the same relationship to the
sulcus prsecentralis superior, as the second frontal furrow to the sulcus
prsecentralis inferior. This can hardly be said to be the case. The basal
or posterior part of the first frontal furrow is, in most cases, completely
identified with the upper prsecentral sulcus. The connexion between the
second frontal furrow and the lower prsecentral furrow is by no means
intimate. A fortuitous communication is in many cases established between
the two, but they are, nevertheless, morphologically distinct fissural
elements.