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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 43

was prolonged upward for a considerable distance into the cuneus, and
divided it into two portions. Examine also PI. rv., figs. 6 and 7. Of
course in the anthropoid ape there is never any trace of the fissure which
in man we have named the posterior calcarine sulcus.

The condition which we have just described as occurring frequently in
the anthropoid is the rule in many of the lower apes. The calcarine
fissure fails to reach the upper margin of the hemisphere. It is important
to note that in no case does the calcarine fissure run directly to the
occipital pole. In both high and low apes where it extends beyond the

Fig. 21.—Orang Fig. 22.—Chimpanzee.

P.O., parietooccipital fissure; 0., calcarine fissure ; c, gyrus cunei.

mesial face on to the outer surface it cuts the mesial border of the
hemisphere a short distance in front of the occipital pole.

From what we have said it will be evident that the cuneus in the ape
does not present the same morphological value as the corresponding
portion of brain surface in man. Only the anterior portion—the part
which lies in front of the stem in fig. 18—is present in the ape. The
hinder part appears to be absent, or blended with the gyrus lingualis.

In connexion with this, the two hemispheres figured in PI. rv. (figs. 6
and 7) are very instructive. They were taken from a new-born full-time
child, and exhibit several marked ape-like conditions. Note especially the

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